Windows 7 won't detect mouse or keyboard

So I recently upgraded to Windows 10 but had to revert back to Windows 7 because it doesn't seem to be compatible with my router (just going to wait for drivers). That said, once I began the revert process, I decided to get my old computer out to use while I waited. I then unplugged my mouse and keyboard to use on my old PC as I didn't have any spare. However, once the revert to Windows 7 had finished, I plugged my mouse and keyboard back in and Windows 7 was unable to detect them.

I understand the problem, I should have kept them both plugged in so Windows 7 could detect them and install drivers properly. However, I think I've tried almost everything... I've tried unplugging and plugging them back in and out, I've tried other USB ports, I tried repairing and reinstalling Windows 7 via the disc (but I can't do anything because the install process won't detect my keyboard fml), and I even went to the extreme of trying to wipe my entire hard drive with Dban, but for some odd reason that wouldn't work too...

Any help with this matter would be most appreciated!

Edit: I can use my mouse and keyboard in my BIOs no problem, it's just that when Windows 7 boots up they fail to work. Furthermore, my motherboard is the Gigabyte B85M-D3H just in case my issue involves going into my BIOS and you need to know the model.