As long as you're sure you've tried booting correctly then you may indeed have a hardware problem. Most times failure of disk media to boot falls to user error or fluke. You can write the latest installer ISO to flash stick from here
to try booting it to repair or reinstall.
If you want to try to force repair or reinstall to see if you can overcome this blockage, you can run free Partition Wizard bootable CD
which will autostart without user input, confirm Windows 7 or it's 100mb System Reserved partition are marked Active, click on HD # to highlight it, then from Disk tab select Rebuild MBR, OK, apply, reboot.
If Windows 7 fails to start you can autostart PW CD or Darik's Boot and Nuke to wipe the HD, which will in turn force the Windows 7 installer to autostart to try Clean Reinstall.
If you have files to rescue then autostart Paragon rescue disk to recover data