1. Put your Windows 7 installation disc into your computer's DVD drive.
2. Boot the computer and wait for the system to boot from the DVD.

3. Select your language from the next menu and click the 'Next' button.
4. Click on the 'Repair your computer' option in the menu.
5. Choose your Windows 7 operating system from the next menu and click the 'Next' button.
6. Click on the 'Startup Repair' icon in the menu to repair your registry.