Recovery mode = factory reset. If that doesn't work, stock rom from Samfirmware, flash with Odin. Problems with Odin flash ? Hopper8's 'Odin troubleshooting' thread stickied in General has all the info you need to get a successful flash (you may need to do a factory reset as well after the Odin flash if you end up doing this). Once you've done that, re-root your phone & try restoring your nandroid, or reinstall custom rom/kernel & start from scratch.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Failure to search is the leading cause of male impotence on XDA
If you don't know how to recover if things go wrong, what are you doing flashing custom roms ?