If system boots up but none of keys work
(including caps lock & num lock which should make led come on)
Then either keyboard has died or ribbon cable to motherboard has come loose
(loose cable is only likely if someone has dismatled & re asembled it recently)
Try a external usb keyboard to see if laptop is working apart fom keyboard
Uhhh, use the setting that puts a keyboard in windows.
Exactly! In Windows 7 & 8 (and maybe XP), at the login screen, in the lower lefthand corner is an icon that lets you choose to use the onscreen keyboard.
Take out laptop battery for few seconds and then place it again and power on laptop. Then you can enter password. (This troubleshooting will work if your keyboard is not working and key pad is responding)