Hi mary Has you got no power to your pc first check the plug ( no lose wires and that the fuse is ok ) if they are ok then it might be the power supply unit ( this is inside your pc) if you have a spare one change them over or get it checked from your local repair shop. i know you said you checked the power supply but i not sure if you have checked the one inside your pc. hope this is of some use if not post back dave The NOSPIN Group is now offering Free PC Tech support at our newest website: http://freepctech.com