|Don't know what type of keyboard you are using, but is it USB or PS/2? |
You may need a PS/2 keyboard connection to access your particular BIOS, if it does not support USB before Windows is loaded.
Some keyboards have those STUPID "F-Lock" buttons that you have to toggle on, in order for the function keys to work at all. So if you have one of those keyboards, you also need to toggle that on during boot up.
Other than that, I am not sure how you can get into your Bios without trying to reset it, or with a PS/2 keyboard. If you can manage to get into the Bios, look for a setting like "USB legacy support", if your Bios supports this option, and turn that ON and then reboot. Theoretically, that should allow your USB keyboard that is plugged into a USB port, to work during the pre-Windows boot-up process. Theoretically.
Sort of the "Which came first, the chicken or the egg", so this may not help.