Old CRT TV's color just faded, how can I fix?

I bought an old, small, used CRT TV from the thrift shop today for playing my Nintendos and whatnot. It was working just fine up until a little while ago when I guess I looked at it funny and now the color is fairly dark. It was almost black and white, though I smacked it a few times and now it's somewhat visible. The TV doesn't have any way to adjust the picture, so anyone have any tips?