You can buy cheap USB keyboards for under $10. You could use that to get logged in. To fix the problems with the laptop keyboard, use Post-it notes to slide under the keys and clean out as much crud as you can, then use compressed air.
My Acer laptop asks for a password before it even starts up, but my P and U keys won't work at all. I've been troubleshooting the problem all day, but can't find an alternate way to get in or a keyboard fix.