Most likely scenario is either the power supply or motherboard died. Check to see if the led near the main psu plug to the motherboard is green. If it is red or not on then more than likely the psu died. If the light to the mb is green then check your RAM and video card as those components going bad or coming unseated would also prevent the system from booting. Once you find the defective part replace with a new one and you should be back up ans running. Good luck & I hope this helps.