Jonathan Lethem-Amnesia Moon

In Jonathan Lethem's wryly funny second novel, we meet a young man named Chaos, who's living in a movie theater in post-apocalyptic Wyoming, drinking alcohol, and eating food out of cans.
It's an unusual and at times unbearable existence, but Chaos soon discovers that his post-nuclear reality may have no connection to the truth. So he takes to the road with a girl named Melinda in order to find answers. As the pair travels through the United States they find that, while each town has been affected differently by the mysterious source of the apocalypse, none of the people they meet can fill in their incomplete memories or answer their questions. Gradually, figures from Chaos's past, including some who appear only under the influence of intravenously administered drugs, make Chaos remember some of his forgotten life as a man named Moon.