'00 Malibu stereo problem--Please Help!!!

My Malibu just got a tune-up and it reseted everything. The screen on the stereo displays "LOC" and I don't know how to program it because I got it used without a manual. Nothing works on the stereo, but everything else is fine. I also don't know how to program or reset the radio presets. If anyone can help me please do so!!!
-thanks

Sounds like the last owner had the radio password protected against theft. Disconnecting the battery put it in this mode. You need to get a dealer to reset it.