Connect an external USB keyboard. There's no reason that shouldn't work fine. That will at least get you logged in to Windows. If you have a keyboard hardware error, which you probably do, then you'll have to get the laptop keyboard replaced.
If for some reason, no keyboard works or you don't have access to an external keyboard, you can click on the little circle/pie-looking-thing which brings up accessibility options and you can open the on-screen keyboard.