Serious Problem! Cant boot any roms or homebrew!

Okay,I have alot of games and homebrew on my 2GB SD card for my " M3 SD Perfect" and for a while it worked great! The thing was a miracle! But then...One day when I tried to put on Phantom Hourglass,it didn't work! And ever since then NO new homebrew or ROMS have worked. They just boot to a black screen. Please Help! My whole almost 120$ modding kit is rendered useless....Well except for the stuff I already have,anything I put on BEFORE Phantom Hourglass works fine,but anything after that doesn't!