Help for resetting code on Kenwood KDC 3022

Last summer I bought a 22' Catalina Sailboat that had a Kenwood KDC 3022 installed inside the cabin. It was working great. My son was the one who knew how to turn it on, etc. Anyway, I must have pushed a wrong button or something because now it says "SP Off". I do not have a manual and do not know what this means. I cannot get it to play. Can anyone help me figure out how to get the radio to play.
I saw some threads that mentioned a remote. There is not a remote control on the boat.