Cause: If the power indicator light on your PC comes on, then your video card or memory may have come loose, usually due to moving the computer, or from repeated heating and cooling of the internal components of your PC.
Solution: Check your surge protector, reset the breaker on it if necessary, check to see if your monitor power light is on, color green or yellow, if it does not you may have a bad monitor, also make sure brightness and contrast on your monitor are turned up, if this does not solve the problem, turn off the computer, open the side of the computer so you can access the memory and video card. remove the memory and reinsert it, do the same with the video card, turn the computer back on. If it still does not come on, bring it in for service. If the power light on the PC does not come on and the power supply fan in back of the computer is not spinning you may have a blown power supply usually due to storms or power surges. Replace the power supply or bring the PC in for service.