Psp version upgrade 5.00 m33-6 to 5.50 gen d2 help pls?

If you mean the files corrupt during the change to Gen, some game CSO's or ISO's only work on a certain version such as M33. If they do corrupt, try saving all your games on the computer, Formatting you Memory Stick, and transferring the games back to your PSP. If that doesn't work, go to a professional gaming site and ask for help. I have an idea of what might happen to your games, but it would take too long in explaining for me right now.