If you have exausted software troubleshooting and it turns out to be a hardware issue (spilt drink, etc) be very carefull when you take out the keyboard. There is a thin cable strip that attaches it to the motherboard and it's very, very delicate and it's usually a pain to detach gently.
The keyboard part comes out as a unit which you can investigate for obvious problems (drink that need mopping up, biscuit crumbs that need blowing out, etc) if you are happy to do that yourself then do it slowly and carfully.
If it's looking like the circuitry pad under the keys then you should be able to get a replacement keyboad from the manufacturor. Probably not as cheap as a regular PC keyboard but it will save you buying a whole new laptop.
