I don't know if this has been attempted before, but I think we should establish a long standing thread of what book each poster would memorize if they had to pick only one with which to restart a barren society.
Since there's no way I could possibly memorize even a short book then I won't let book length affect my decision. I'll pick The Dark Tower series by Stephen King. Sucker's 4000 pages long but it's worth a read or three!
We come into this world naked, screaming, and covered in blood. Why should the fun end there?
OK, in that case... "Hard Boiled Wonderland and the End of the World" by Haruki Murakami.
But I guess it wouldn't do to memorise the English version, and I don't speak Japanese, so as a second choice I'd go for "Kruistocht in Spijkerbroek" (crusade in jeans) by Thea Beckman, one of the classics of Dutch children's literature, and one of the reasons I started reading in the first place so many years ago.
Good choice there Mylilprincessaly, although calling it a translation is stretching things a bit, it's more like an entirely new book. I'd go for "One Hundred Years Of Solitude"; a bit of humour, a bit of tragedy, plus it would preserve a bit of the Bible and all the other major works that it references.
I've already memorize most of Harry Potter, so I'd choose that ^_^ But other than that? "A brief history of Time" by Stephen Hawking and "Beowulf" would be on my list!