Format, your only real option. I'm assuming it is an R4 you are using it in. I've had cluster fucks with mine a few times already. Just keep a back up of everything your put on it and back it up once in a while.
AW thats gay... Welll I wish i can back up the corrupted files and everything and get my saves!!! i forgot to back up saves.. long story. I onlly got games though. For me the saves are MORE important than the saves (of course). Well tthere goes about 40 hours of dddddds playing going to thrash. And yes im using an R4
Yeah dude, like I said keep an extra folder named R4 or whatever and when you put something new on it put it in the R4 folder as well. Back up saves once in a while too, i do it maybe once every week out of habit. I get OCD about my dataz.