One of the GFCI outlets in the kitchen stopped working. So did several other outlets in the kitchen. And several other outlets in adjoining rooms. The test/reset buttons were completely inoperative.
Had we done some significant construction or repair work, I might wonder if there was a bad wire somewhere in the walls, but we have done nothing like that, so I decided to replace the outlet -- which had probably failed. Nope. The test/reset buttons are still inoperative.
My guess at this point is probably the circuit breaker has failed. It behaves normally -- but I understand that is also common when circuit breakers fail -- although it seems unlikely that a circuit breaker would fail after only six years of use.
Our electrician returns tomorrow. When it comes to replacing circuit breakers, I would rather a professional to do that.