Some weeks ago both Microsoft keyboard and mouse for my desktop stopped working. First thing I did was replace the batteries. Nope. They are wireless so tried to reactivate the receiver. Nope.
Went to Staples and bought a new wireless keyboard and mouse for only $18. Amazing what you get for that price. Smaller, but works.
Two weeks later, the old mouse is still on the desk. I bumped into it and the courser moved! It works again for some reason, maybe the receiver reset. Nothing on the keyboard to go so finally, tonight is trash night.
I took the cover off the battery thing, pulled out both batteries. Then, headed to the garage to gather up some things for trash so leaned the keyboard, with no battery cover, against a cabinet. A third battery fell out!
Looking at the brand, it had been in there for some years and not seen, not replaced when the other two were at least once maybe twice. Put in THREE AA batteries and now it works.