IF you think it's worth doing, the keyboard on a laptop can be replaced fairly easily and not too expensively. I've done so myself. Used a google search to find a replacement keyboard for the given model, ordered one, and installed it myself in a few minutes.
Of course if the computer is more than three or four years old it's probably not worth doing. Just use the external keyboard and mouse until you replace the unit. They are much easier to use than those little laptop keyboards and track pads, anyway.