Three years ago, I installed two GFCI outlets under an outdoor shade, but this morning, when I was using an air fryer with one of them, the power went out. I went to the main electrical panel and it didn't seem to be tripped. Press "Test" and hear a sound. But "Reset" cannot be pressed. "Test" no longer responded after the first try. I used the circuit tester, it indicated that both outlets were out of power. If the circuit has not been tripped, why were the GFCIs out of power?
Never trust a breaker is not tripped just by looking. After a few years dust and grit accumulates in breakers and many times the handle will not move when it trips. I will generally run a finger down all the breakers, pressing them lightly towards the off position. If one has tripped, it usually will pop into position when you touch it. And any time there is doubt, a quick off-on never hurts.
But, if breaker has not tripped, then your GFCI died. It is very common for these to stop working at any time. Some don't last a year, some have worked for decades. After resetting breaker, if reset on outlet still won't engage, it's time to replace. If you have a non contact voltage detector, you can pull off wall plate and check for voltage on the right hand side of outlet. If you have voltage there, it is for sure a dead GFCI. If no voltage there, it's in the breaker.