**EDIT**
I failed to notice this was in the Laptop support section. Disregard the USB port advice. If the laptop was one you purchased as a pre-build, it will most likely be using a cheaper economy keyboard that is not easily replacable, practically. As for problems for why it might not be working, sometimes your PC simply needs a restart. If that fails, I would say it is more-than-likely an internal issue with the connection with the motherboard (Since these kinds of keyboards connect internally with the laptop's motherboard/monitor display) Have you accidentally spilled anything on the keys? Even a minor splash of water or small amount of food can disable the keys/cause malfunction.