Was anything spilled or dropped on it? If no, try the following...
1. Uninstall your keyboard driver(s).
2. Reboot the computer. Yes, I do mean without installing the driver(s) again just yet.
3. When the computer restarts it should seek to install the drivers again itself.
If this doesn't help, try turning off the laptop, connect an external keyboard, and then turn the laptop on. Do the keys work on that one? If yes, you may need to replace either those specific keys, or the whole keyboard.