Black screen with flashing underscore

I encountered this problem two days ago while using my computer (hp pavilion elite) and it sht off on it's own. I tried to restart and it won't boot windows. Just a black screen with a flashing cursor at the top. I searched all over these forums and haven't found a solution that works. So far I have done a restore point, tried to reinstall windows from a recovery disk, I've used command prompt to Fix the boot record. Diagnostics says my hard drive is fine and I can see the newly installed windows 7 on my hard drive via the recovery disk boot. But when I try to boot from hard drive it still goes black. I don't know what I'm doing wrong. Or if there is any fix possible. Any help or advice would be greatly appreciated. Thanks