Keyboard not working on log in page

I have a Dell Inspiron 15 Windows lap top. I am not able to log in because my letters will not work. The numbers do. Does any one have any ideas?

Hook up a usb keyboard and see if the letters work, If they do then you can assume its most likely a keyboard issue. Also try booting to safe mode and see if the letters work there.

Thank ou for your help. I used a usb keyboard and the same thing happened. I could not log in in safe mode, but I finally hit F12 and ran a complete diagnosis which took hours. It indicated that nothing was wrong, but the keyboard started working. The next day the keyboard stopped working again. I repeated the F12 login ran another complete diagnosis and received the same nothing was wrong diagnosis but the keyhboard started working again. So far it still works. I am not sure what happened. What do you think?

If it keeps happening you could try reinstalling windows.