Trableshoot

First, remove and CD/DVD/USB disks you may have in the system. Reboot, fixed? If not, check to make sure your hard-drive is seen in the BIOS. If it is, set it as the first boot item in the boot order, reboot. If it still fails, if the disk making any odd noises? If yes, it's a bad drive, buy a new one, install Windows on that. You can try the disk as a secondary in another computer and see if it will read any of your files to save if you did not have backups.