Your pc needs you to go into SETUP (i.e. the BIOS) to change something. But if you cannot use the keyboard to get in you may need to do something else.
First of all, are you using a USB keyboard? If so, try a ps2 keyboard (small round connector).
Or try a different keyboard even though you know this one works ok.
If not, then it sounds as if you may need to remove the CMOS battery (but only as a last resort).