HP Pavilion m8120n will not load fan just run

Hello,

My computer was working okay till I woke up and found it off. I tried to turn it on and all it does is run the fan. The dvd drive flashes but there is no beep and the hard disk light does not come on or flash at all. I have tried turning on and off but same problem. The funny thing is when I turn it off and unplug it when I plug it in again it will turn on by itself and turn off and on once before the fan just keeps running and nothing happens. Can someone please help..

I leave computer on 24/7 but never had this happen. I have unplugged everything and it will keep turning off and on in an endless loop. If I have cable modem ethernet plugged in it will show my compter registering on modem but the fan just keeps running and hard disk light does not come on at all.