Keyboardtrouble

My keyboard is having problems. It says it is stuck on number lock ,but it will type some letters. Half of the letter keys do not works and the numbers create series of letters and symbols. I have not dropped my computer or spilt anything on it. I did lift up the keyboard from the holder a day before this all started happening, but that shouldn't have made it do this. Is there any way I can fix this myself, have someone else fix it, or would it be better if I just replaced the keyboard with a new one? How much do laptop keyboards cost, as well?