Hi,
Insert your windows 7 disk in you computer and restaart you computer.
When asked boot from dvd
Click next
Repair your computer; on the next windows you will have the choise betwen Startup repair-System restore-System image recovery
Try system startup repair first, if it does not work move on system restore and if no success and if you created a disk image before System image recovery.
If all fail renove your hard drive, install it into another computer and retreive your data before you continue.
Let me know how you are going
Edouard
Best regards......Learn something everyday