Audio Systems: car radio, control circuits, car radio

Question
My "91 gmc step side has just recently developed a problem after being sat in the drive way for four months.  I started it up and the radio will no longer allow me to change the stations or let me turn up the volume (along with adjusting all the treb bass etc..) what could have happened here 'cause I have no clue.

Answer
Mike,
Have you changed the battery or given your truck a jump start? A jump start may have damaged the control circuits. Also was you truck stored in a very damp location?. The problem may be due to corrosion on the circuit board/s If you can power up the stereo but several buttons do not work I would first take a close up look at the circuit boards for any signs of corrosion.

TOM,
T&D ELECTRONICS