I opened up Steam and went to Terraria, but instead of saying "play," like it usually does, it said "install." So I installed the game, even though I had never uninstalled it in the first place. After the install, everything was exactly the same except one of my characters was replaced with a blank character slot with 0:00 play time.
All my worlds were still there, as well as the one other player I had. I also found a world called Unknown World and loading it causes the game to crash. It's actually the size that's unknown it has no name.
How can I get my character back?