Hi, I'm Sudipto. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP
I am extremely sorry for late reply. The problem you are facing can be caused by two reasons, One, if the keyboard is defective or two, if the keyboard driver is corrupt, to find out the exact fault, you have to connect an external USB keyboard with the laptop. After that, restart the laptop. If you see that, the external keyboard is working then, it will be confirmed that the inbuilt keyboard is defective and in that case, you have to get it replaced from any local repair shop.
If the laptop is less than one-year-old then, you can get the keyboard replaced from Acer, without any charges. Let me know if you need any further information, otherwise please remember to give a positive rating, as that is the only way I am compensated for my time and effort.