Blank Book

The proofreader *really* needs to lay off the sauce.

This is when a character picks up a book and sees it is essentially empty. It's just a cover (possibly even without a title) pasted onto a blank book, or one filled with nonsense words like Lorem Ipsum over and over, or that just simply stops partway through. Why is this book blank? There's a few less than good reasons for it.

Type 1: It may be that the character is trapped in a Lotus Eater Machine of some kind and the book being empty (or filled with unintelligible and unreadable gibberish) is a sign that the Master of Illusion got sloppy, an Author Existence Failure, or the dreamer can't remember it right.

Type 2: It's also possible that the character is in some kind of stage filled with prop books, or the book is a deliberate fake intended to deceive.

Type 3: Someone (or thing) may have "stolen" the contents of the book and left it completely wordless in the process. In fact, some words may literally fly off the page or drip off as wet ink.

Type 4: Lastly, the book being blank could be an Aesop for knowledge or lack of it. Perhaps the famed book of wisdom is blank because the person finding the book is supposed to write out the important knowledge himself because having gone through the quest to find the book he now has the wisdom to write the book of wisdom himself. A case of All That Glitters. Or if the book was a blank holy text, it shows that character is denied the knowledge that will save his soul because he is now beyond redemption.

Examples of Blank Book include:

Anime and Manga

In Tsubasa Reservoir Chronicle, the book was blank for the first person to pick it up. Once handed to another person, it was filled with the first person's memories for the second to explore.
In ×××HOLiC, there was a demon that ate words from books. It was eventually tricked into eating the words on a Protective Charm, making it Sealed Evil in a Can.
In the seventh arc of Umineko no Naku Koro ni, Will attends Beatrice's funeral. In her coffin, there is no body, just a book. When Will opens the book, the pages turn to petals. It's later shown that the book contains Battler's final iteration of what happened during the Rokkenjima murders - an iteration that is only to be shared between himself and Beatrice.
One of the Dolems traps Kamina in a Lotus Eater Machine in an episode of RahXephon. While there's plenty of strange things going on, one of the first that he really notices is that every book is blank.

Comic Books

A Calvin and Hobbes strip invokes this trope. Calvin uses this as an excuse for not doing his homework: "I tried, but the book publisher didn't use the proper print fixative. Needless to say, when I picked up the book all the letters slid off the page and fell on the floor in a heap of gibberish!"
In Grant Morrison's Batman, the Joker's Joke Book is supposedly written in an ink that only the insane can read. It's intentionally unclear whether this is literally true, or simply a way of saying a crazy person will imagine there's writing in it. Either way, to most people, it's a Blank Book.
The Wisdom Of Lobo, an actual book included in a three-book Lobo slipcased set back in the 90s. It was blank.

Film

Cast a Deadly Spell. A man steals the Necronomicon and sells it to mobster Harry Borden. After Borden pays for the book and the man leaves, Borden opens the book and discovers its pages are blank - it's a fraud.
In 1408 the protagonist in desperation picks up the Gideon bible in the hotel room he is trapped only to find that all the pages are blank.
In Dark City, John Murdoch discovers that a picture book he drew in as a child is now completely blank. For extra Paranoia Fuel, when he tries to show it to a cop later, it's filled out.
Happens at the beginning of Inception when Cobb steals the documents from the vault inside Saito's dream. When Saito catches on that someone is trying to steal his secret memories, he checks the documents in the vault to find literal Blank Pages placed there by Cobb. But now that Saito is aware that someones going through his memories, the pages in the document stolen by Cobb have most of the content blackened out, as Saito tries to block him out of his subconsciousness.
Happens in Kung Fu Panda: The Dragon Scroll turns out to be totally blank. Instead, it is a mirror, meant to prompt the lesson that true strength comes from within rather than spelling anything out.
This happened with Twenty Thousand Leagues Under the Sea in the film version of Sphere. It wasn't blank, but just stopped where the reader was too scared to read past that page while he was a child.
Pleasantville: The library's books are mostly blank until the male lead exposes the locals to the concept of reading for pleasure, at which point new words appear.
Pan's Labyrinth: The Faun gives Ofelia a blank book and instructs her to open it when she is alone, whereupon the instructions for the tasks she must complete will appear to her. The book also lets her know about her mother's impending death in childbirth by displaying a blood splotch that takes the shape of a womb before spreading to fill the entire page.
In Warriors of Virtue, the child protagonist is asked by the Big Bad to read from the magical Manuscript and tell him what it says. The Manuscript suddenly shows blank pages, to which the protagonist says "Shit happens."

Literature

In the book Conrad's Time Machine, the inventor had huge shelves of "effectively 100%" original first edition books. Effectively 100% in such way that all books he or anyone else had and will read, glance though or touch are real first edition books. What is actually there is around 0.1% real first edition books and rest are just titled blank books.
There's a variant on the social climber's "Prop Books" in The Great Gatsby that may or may not be worth noting here: Gatsby's library is full of real books—but the pages are left uncut, meaning he doesn't actually read them. Owl-Eyes notices this and calls Gatsby "a regular Belasco", complimenting him on the thoroughness of the illusion.
The Historian by Elizabeth Kostova features several books that are blank except for a picture of a dragon in the middle.
In Tanya Huff's The Keeper, the protagonist tries to restore a decayed journal, but a "word spider(?)" got into the word-restoring tupperware the book was in and caused the words to literally drip off the book, much to her horror.
In Harry Potter and the Chamber of Secrets, Tom Riddle's diary is effectively blank until someone writes into it. After Harry destroys it with the Basilisk venom, it goes blank for good, though not before bleeding ink.
Played with in the final trilogy of the Sword of Truth series. Richard finds a book that is supposedly a user manual for his unique and powerful form of magic, which has always worked entirely on instinct, as he has nobody around to teach him how to properly use it. Unfortunately, when he tries to read the book, it's blank, which at first he takes as being because he's lost his magic, as the series has previously established that magic books are charmed so that if you don't have magic, they appear blank. At the same time, the Chainfire spell has also been shown erasing other books, so the reader might attribute the blank pages to that instead. Eventually, however, it's revealed that the book was meant to be blank, and represents the final, unspoken Wizard's Rule.
In the Animorphs Prequel The Andalite Chronicles, the Time Matrix creates a miniature universe based on the memories of Elfangor, Loren and the future Visser Three. Elfangor leafs through a book in Loren's faux bedroom and notes that it ends halfway through; he reasons Loren didn't finish the book's real-world counterpart, giving her mind nothing to fill in for the rest.
The Great Samuel-Pepys Fiasco
In The Stormlight Archive, one of the devotaries (religious orders) uses a blank book called The Book of Endless Pages as a metaphor -- the book cannot be filled because there is always more to learn.
One of these appears in The Chronicles of Prydain; it's discovered text appears when the pages are viewed with a particular kind of magical light.

Live Action TV

When Willow's Super-Powered Evil Side emerges in Buffy the Vampire Slayer, she absorbs the text from all the magic shop's books on dark magic. Her friends later try to find out about the magic she's using, but the books are now blank.
- Another Buffy the Vampire Slayer example: The book used to seal Moloch was blank until the sealing ritual was performed, at which point it would fill up with words. When Willow scanned it into the library computer, it became blank again, as Moloch was released into the internet.
In Dark Oracle the eponymous comic book would inevitably arrive with most of the pages blank. As the episode progressed, pages would fill in, eventually revealing whichever horrific future Cally and Lance had to avert.
In Star Trek: Deep Space Nine, Bashir realizes he's still in Sloan's mind when his copy of A Tale of Two Cities has "It was the best of times, it was the worst of times." at the point where he left off; because he hadn't finished the book, Sloan's mind filled in the unread parts with repetitions of what he had read so far.
- The Tome of the Pah'Wraiths is a forbidden and blasphemous text in the Bajoran faith. But when it is opened, the pages are all blank, confounding those who would seek the evil knowledge within. Only after a virtuous man is murdered while trying to keep the book from evil hands and his blood drips onto the pages does the actual text appear. Even, then only the Chosen One of the Pah'Wraith can actually read it; anyone else who tries risks being supernaturally blinded.
In the Doctor Who episode "The Big Bang", Amy is given River Song's diary as a wedding present. However, the book is blank because the Doctor has been erased from time. Once Amy remembers the Doctor and brings him back, the diary's contents return.

Video Games

In the city of Windhelm in The Elder Scrolls V: Skyrim, there's a book titled The Book of Fate in Calixto's House of Curiosities. It was apparently discovered in the Arcane University in Cyrodiil and purports to contain the reader's fate. When the Dovahkiin reads it, the pages are blank. Make of that what you will.
One of these appears as an equippable weapon for Charlotte in Castlevania: Portrait of Ruin. While it is a pathetic weapon, it is necessary for a sidequest, in which the Tortured Abomination Gergoth must be slain with it.

Webcomics

Lampshaded in Ninth Elsewhere:

"How ridiculous, my own subconscious is mocking my goals."

In this Xkcd comic, a man has a shelf full of blank books, which he uses to make a profound point about imagination. His friend simply asks, "Who sold you all these blank books?" The alt text reveals the comic is actually a metaphor for homeopathic and "alternative" medicine.

Western Animation

In Batman: The Animated Series, when Bruce Wayne was trapped by the Mad Hatter in a Lotus Eater Machine, one of his first clues something was wrong with the perfect world was that all the books were unreadable. (Hence the page image).
The Justice League cartoon had an episode where Green Lantern, Hawkgirl, Martian Manhunter, and Flash got transported to an alternate universe where the Silver Age heroes John Stewart read about as a boy are real. Midway through, John gets suspicious that the world isn't all it seems, and goes to a library, where he finds all the books are blank.
Jonny Quest: The Real Adventures: Villain Ezekiel Rage constantly quotes from "The Book of Rage". When Jessie finds it, she discovers it's completely blank except for a picture of Rage's dead family.
Thundercats 2011: Sought-after Great Big Book of Everything and Tome of Prophecy and Fate the Book of Omens, at least, in its appearance as a book. It's actually a Magitek computer
Ed, Edd 'n' Eddy: For some reason, the Kanker sisters have a shelf of blank books in their trailer. Edd seems to have a minor freakout when he discovers this.

Real Life

In the line of "prop books", a social climber's library may be filled with shelves of these, there to look impressive rather than be read. Or they may be real books that have never been read at all. This sort of thing has been mocked in more than a few, um, books.
Fake books may also be used on movie sets. For example, the books in Dumbledore's office from the Harry Potter films are actually phone books with the covers changed.
It is sometimes the case that dreamers can not read in their dreams.
Once a publisher couldn't make a textbook before the deadline and chose to send the textbook committee in California a book consisting only of a cover and blank pages. Six out of the ten members gave it ratings, and favourable ones. This happened during the time when Richard Feynman worked there, and he was really interested, so Hilarity Ensues. At least, someone learned from it—the public about how well such a system works.
When prototyping the graphic layout of a book/poster/website/etc., it's common to use deliberately unrelated placeholder text (such as "Lorem ipsum", a fairly standard passage of broken Latin) so that the actual content of the text won't act as a distraction.
Books written in Braille seem to be completely in blank... at first sight, at least.
There have been a few cases where a manual has had all its pages deliberately left blank.