Ensure that when you downgraded to Windows7 Ultimate from Windows8 (sounds like it was on a desktop right?), you reinstalled without formatting the hard drive. Downgrades almost always require this unless you use Partitioning Software such as Partition Magic or other. Unfortunately, when you do this, and you have a name brand desktop such as Dell, HP, Acer, or similar it will ask you to wipe out ALL partitions which you must say "Yes" to. OR IT WILL NOT WORK!
So, prior to performing this destructive downgrade, you should make sure you have Factory Windows Recovery discs for your Windows8 that came with that computer, as it will be gone after your Win7 Ultimate downgrade procedure. If you didn't get Discs that came with your...