Be sure that the DVD you are using is for the same edition of Windows 7 that you are trying to repair – for example, Windows 7 Home Premium, 64-bit or whatever specific version that you have. A full installation disc can be used for repair even if you have an OEM system. No product key is required in this process.
- Put the disc in your optical drive and restart to boot from the DVD. You may have to change the boot settings in your BIOS if booting from a CD/DVD is not enabled. (See how here.) Watch for the “Press any key to boot from CD or DVD” message.
- On the "Install Windows" screen, make the appropriate selections for language, time, and keyboard, and then click “Next”.
- On the next screen, click “Repair Your Computer”. Do not click "Install now"
- In “System Recovery Options”. select which operating system you want to restore if any are listed. It will be blank in many systems with only one operating system.
- Click “Next”.
- The “System Recovery Options” screen shown below will open.
- Select “Startup Repair” or whichever option you wish to apply.