Light Music.
A futuristic self-aware city which stores data in its very structure is attacked by terrorists. In an act of self preservation, after a section is cut off with no redundant backup, the city downloads a couple library categories into the brain of an unwitting resident. His whole identity is replaced by the entire human category of Wild West movies, comics and books, along with some scientific data on radio communications. His memory erased, his entire personality is now Radio Cowboy.