|Your USB keyboard is probably not plugged directly into your mothernoard's rear mounted USB port DIRECTLY on the motherboard OR it is a wireless keyboard. USB ports that are run through hubs or expansion cards and sometimes even front ports are NOT active UNTIL Windows is fully started and the drivers are loaded. Wireless keyboards are also not active until windows is fully up and running so look for that old wired keyboard and plug it in for set up. Plug the USB keyboard into one of the original rear ports within the tight group of connectors along one side of the rear of the computer (not bottom ones that may be on a card or on an internal expansion hub).|
If this is not the case (a very common one) look to borrow an old keyboard with a PS2 connector (you may have one stashed somewhere) and use that to set up.
You have to be a little bit crazy to keep you from going insane.