Biostar M/b won’t recognise keyboard

My Biostar M5VNB socket 7 motherboard with AMD K6-2 500MHz CPU suddenly stopped recognising my PS/2 mouse when I booted up. I added a serial mouse and the problem was solved. Then I realised the keyboard was not being recognised – no error message or anything. I set CMOS to defaults and now I get a message press F1 to continue but of course since the keyboard is not recognised nothing happens. If I could get the keyboard to work I would be able to use my computer again. Any solutions