There is no "disable or enable" keyboard option. You need to check the connectors on the keyboard to the motherboard, which involves opening the case some. Look for screws on the bottom, the ones holding the keyboard in place should be marked with an icon. If the connector is fine, you need to get some hardware replaced, either the cable or the whole keyboard assembly.
Does the keyboard work at all, can you hit the BIOS key to enter the BIOS?