I would start right at the breaker box---begin the search at the beginning of the run----bathrooms often have more than one circuit---
Look for a gfci breaker---it will have a handle and a push button---
If that yields no results---flip all breakers on and off just in case you have a partially thrown breaker--
If that fails--I'd open the cover and test each breaker---
If that fails----look for a tripped gcfi somewhere in the house or outside----houses built in the 1970s often used one gfci outlet to protect the whole danged house---
When was your house built? You do have a tester with two wires?
House was finished at the end of 08. All of the lights are on the same breaker, yet some are still working. Nothing else is tripped anywhere in the house that I can find. Unless there's a hidden gfi somewhere. I do have a voltage tester.