iMac w/Windows 7 suddenly lost USB keyboard, mouse

My dad's iMac (21", late 2012 I believe) recently has stopped responding using the USB mouse or key board. I have tried restarting, unplugging/replugging, different mouse, different keyboard, etc. I also attempted to reinstall the BootCamp drivers disk (didn't work), connect from Thunderbolt -> HDMI -> USB male in an attempt to use an external USB enabled screen, but that isn't working either.

Upon searching I was told that reinstalling the two devices via the Mac side of things might solve the issue. The problem is that there is no Mac side anymore - it is one partition as it is only used with Windows 7.

I have also read that there is a USB 3.0 upgrade that makes the 2.0 devices incompatible. What I have observed so far:

Keyboard - no reaction
Mouse - no reaction
Alternative keyboard/mouse - no reaction
iPhone - no reaction, no charge
Mouse #3 - red light (surprisingly) but no movement

So now I'm kinda out of options. I cannot access the computer in any shape or form, and it will not respond to any USB (other than the one mouse red light). There used to be a bluetooth Mighty Mouse that was connected which I'm trying to dig up to circumvent the issue, but I have a feeling it's with my brother quite far away.

Any suggestions?