Windows XP Logon. Suddenly, keyboard doesn't respond. Mouse is OK. Safe mode, etc.. doesn't work.?

replace your keyboard/or try your keyboard on another computer to see if it works.if not look at your connection on your computer check to see if the tongs in the end of your keyboard are straight. if so you should be ok. run a virus check. or take it to have it cleaned. and get out of safe mode. that could be your problem.