I have an Hp pc dual core .... IT was working fine yesterday n wen i tried to turn it on 2day it just would not..
and i checked and the power box is working bcause there this light that turns on wen i plug the power cord.. any reason why this is happening ???

If there are no beeps then check the cables again or VGA . Otherwise u may have a bad MB.

have you done any recent upgrades or been inside the computer? check all your connections... if it doesn't do anything when you push the button its either the switch or the mobo... possibly psu.