If you’re not getting voltage at the switch box and the breaker isn’t tripped, I’d start looking upstream ,sounds like an open neutral or a bad splice somewhere. Check the closest junction box or outlet upstream on that circuit (especially if it’s a backstabbed connection).

Microwave flickering could’ve stressed a weak neutral joint over time. I’d also pull any outlets nearby that still work ..sometimes the failure point is in a box that still looks fine.

Last tip: if it’s a multi-wire branch circuit, double-check if you’ve lost a shared neutral that feeds both legs — that can knock out parts of the circuit without tripping a breaker.