Why is my keyboard not working properly?

First try a USB external keyboard. Does it work? I am assuming it does. Fix any boot issues then. Now test your internal keyboard with a Word Program - type every key checking if any of the keys do not work. If some do not then determine which ones. I had an issue with only one side of the keyboard was working on one laptop. The fix was replacing the internal keyboard. Anyway, you might have noticed if there is an issue with some keys sticking, if so then maybe there was a liquid spill. In any case you could check if the flex cable is loose. Just google replacing keyboard <MODEL #> laptop keyboard on you-tube and see if anyone has recorded a keyboard replacement for your model. Check your keyboards connections if it is loose and see if it is or not. If it is try and re-seat the connection. Test it between boot ups and if it is loose ..you should be able to re-plug the flex cable in until it is tight. If it still doesn't fix the it might need replaced. Google the replacement cost and then make your decision. You could also just use a cheap USB keyboard.