Maybe you have a stuck key or button... press each one a couple times.For some reason my trackpad stopped working too. Exactly the day I am spending 9h in the train, leaving Toronto (where the closest MS store is) and when I wanted to work a bit.
It's like the click is always clicking, making the keyboard completely useless.
The only thing I did was to wipe my keyboard with a Lysol wipe.
If the keyboard is not able to survive the wipe, then it is annoying.
I have a couple of these since I have more than ne surface I think I'm going to start carrying a spare.