What AC is saying is that it sounds like a hardware fault, you may be lucky and it just needs the cable re-connecting but if not then it's probably a new keyboard at the least, at worst it's a new main board in the laptop.
It's not really a job I suggest anybody tries if they are not sure what they are doing, laptops are not the easiest things to get to pieces and the connectors for things like the keyboard are very easy to break if you don't know exactly how to release them.