Keyboard specific keys stopped working

Hello,

My space bar, enter key and backspace all stopped working at once. It is not a notebook. Tried reinstalling drivers, but nothing seemed to work. Switched operational systems (from Windows to an Ubuntu), and that did not solve my problem either. Any clue to what might be happening? I though this was not a hardware thing, for all of them stopped working at the same time. But then again, I have no idea what is causing the problem.

Thanks!