Download and Install Keyboard Fixer
freeware. It can fix this problem.
as a 7 years experimented technician, I come to conclusion that Acer is one of the worst computer brand... The best way to fix the problems of keyboard not working is to factory reset the computer, but it will be temporary because the same problem will surface again after a period of times... the problem is in the board, so Acer needs to address the problem and make a change to the way the manufacture their computer board.