Yesterday I was on my computer, its an HP Pavilion dv9308nr Notebook PC, when it suddenly put itself to sleep. Or at least the monitor went black. I did what I usually do to bring it back up, which is shake the mouse and if that fails, quickly push the power button. Well, the mouse was dead, the little optical light was off, and the power button didn't do anything, it just sat there. So I did what I would usually do if I couldn't get it to restart which is use the power button. Now it's been doing this sleep thing pretty often lately and it always comes back on after I restart it, but this time nothing happened. The lights on the keyboard came on, but the screen stayed black. The fans didn't even start up. It would stay this way for about 30 seconds and then restart again, and it just does this over and over again until I turn it off. Nothing pops up on the screen its just black. It won't boot at all.
I had a suggestion thinking that it was overheating, but I had it sitting at this point so it was getting plenty of ventilation, so I'm not sure what to think. If anyone could give me some help I would really appreciate it.

Also, I started it up this morning and the fan will go on for a couple of seconds, then go off and they cycle will continue as before.

Thank you