Originally Posted by
Chaltione
Pull out the power plug and keep it disconnected for up to 5 minutes. Your power supply may have had an automatic fuse that needs resetting.
Would be nice with some more information about what happens when you try to start up:
Do you have any motherboard lights when it's "off" that you used to have?
Does fan start spinning when you push the power button?
Do you hear any noises beyond fans if they start spinning?
If you're getting no fan spinup or sounds, but have passive lights on the motherboard, try checking the wiring to the power button.