To download the Windows 7 ISO, go to Microsoft's official Download Windows 7 Disc Images (ISO Files) website, enter in your Windows 7 product key, hit the Verify button and download the ISO. ISO files are disc images that can either be burned to a DVD, placed on a USB stick or run natively, as if the disc was inserted into the PC. If you can't find the discs, then don't worry, as Microsoft offers Windows 7 and Windows 8.1 ISO files for legal download.
