Try putting in the recovery disk & booting. If it doesn't try changing the boot order in the BIOS, if you can.
If you can't see the BIOS, then it might be the BIOS battery.
Use anti virus, backup your data, use google.
POST BACK EVEN IF THE HELP DOESN'T HELP.
A Thank You would be nice if I have helped.
UK MP's are thieving scumbags