What in Windows 7 is not working? Can you tell us specifically what's wrong?
Try running the SFC/SCANNOW command. It will fix any corrupted or deleted files. Run the command followed by a reboot, three times. SFC /SCANNOW Command - System File Checker
If that doesn't work, try restoring your computer to a point before the problems started using System Restore. System Restore
You could also try doing a repair install using the original Windows 7 disk. Repair Install
If you do not have a Windows 7 disk, you can create one. System Repair Disc - Create
Hope this helps,