Always keep a basic PS2 keyboard around for such emergencies. $17.
I guess you are using a wireless mouse/ keyboard combo. Are you telling us everything, did someone spill coffee or Coke in it? Both are acidic.
What battery? The keyboard battery or the CMOS battery? If you are using rechargeable batteries in your keyboard/ mouse… stop. They can easily overheat and spill acid into the keyboard, ruining it. You also have to deal with battery memory, which runs amuck in those darn things. It’s less expensive in the long run to use normal 2As/ 3As.
I guess you don't have an IT guy to call. Use the mouse to completely delete the drivers for your old keyboard. Leave nothing, not even the folder. Reboot, then re-download/ install the latest drivers from the company website.
Sometimes Win will “remember” settings on corrupted drivers and reinstalling will not work unless the drivers are completely removed.
If that doesn’t work either buy a new keyboard or, if you are sure the old keyboard is still good, look at reimaging your machine.