I'm sorry, I'm trying to understand what you just said. A world in which there are no libraries? How is that possible, if there's anyone left at all? Libraries aren't just buildings, books on shelves. They're ideas, stories, and stories you pass on, tell to others. You can write them down to keep them longer, to share them further, but you don't have to, because they still survive in the people themselves. So long as anyone remembers, they're still real.