Were your keyboard and mouse working fine before you installed the drivers? It's possible that you installed the wrong USB drivers.
Those drivers should have just been for your USB 3 ports as Windows 7 supports USB 2 natively. Try connecting your keyboard to one of the USB 2 ports on your mobo. Also, some mobos are finicky about which ports they like the keyboard/mouse connected to. The safest best is to connect your keyboard to one of the first two port (pick the one closest to the motherboard).
If that doesn't work, try to see if you can still boot into safe mode (hold F8 as windows boots) and uninstall the bad drivers from there.
Final option might be a repair install of Windows 7 (which won't delete your data), of just a full clean install since this is a new system. If you go this route, consider installing Windows 10 instead. It works better with more modern technologies that Windows 7 didn't have in mind when it was built, and it has native USB 3 support (so no need for drivers). I realize that not everyone likes Windows 10, so just take this as a suggestion.