What attempted repairs have you tried? Did you do a system restore?
If you already tried system restore, I would suggest going through the steps for Troubleshooting Windows 7 Failure to Boot
and closely following that guide.
For the step to use SFC /SCANNOW : Run in Command Prompt at Boot
to check your system for errors, make sure you select the correct drive letter as it may not be C:. It could be D:, E:, F:, or even G:. It will not be X: To determine which drive letter contains Windows, find the drive with the Windows directory using the following command prompt commands:
etc. until you see Windows listed as a directory.