You probably just deleted somthing you shouldnt have. Go to restore ps3. make sure you deactivate your system first, by going to account management and sytem activation. Then restore your ps3 sytem. I recomend doing the full restore as you probably deleted other stuff you shouldnt have as well. lol. This will almost definitley fix your problem. Unless you had the MW2 disc in when you were doing all that deleting. lol an easy way to tell if the disc is f**ked is just take it and play it on another ps3. If the disc works then the restore will definitley work.

Thanks this worked! Playing the game atm, but do i need to install my cfw again? I wa on kmeaws before, how do I check, it doesnt say on system info just 3.55. Is it safe to install it again?