I have been having issues with ground fault outlets in the bathrooms in my house for some time now. Usually they would miraculously correct themselves and I don't know how or why. The other day I had the usual issue. The outlets and the lights would not work in the bathroom along with the light in a room on one side of the bathroom and 2 outlets on the same wall in a room on the other side of the bathroom. I tried resetting the outlets. (there are 3 GFCI outlets in this bathroom.) That did not work. I tried replacing the one GFCI outlet that I thought was the problem. That did not work. My final attempt to correct the issue and isolate where the problem was to remove all 3 GFCI outlets and install 3 standard outlets. This still did not fix the problem. I also thought that on the slight chance that the issue may be with other GFCI outlets in the kitchen and another bathroom, I remove those and replace them with standard outlets as well. Still no good. I determined that the outlets in the kitchen and the other bathroom are not the issue. The standard outlets in those two rooms work fine. At this point, there is power at the three outlets and at the two light switches in the problem bathroom but no power going out. The lights do not work and an electrical device does not work when plugged in to any of the affected outlets. My next step is to call in an electrician.

Strange to have 3 GFCI's in a bathroom unless they are very widely spaced. In addition, they should not be powering outlets outside the bath. GFCI's don't reset themselves. I believe you have a loose wire on the breaker or another supply wire to the bathroom. How old is this house, it should have dedicated bath circuits. If you have power in, you have power out unless you have wired something incorrectly. Outlets rarely fail. Tell us how you are measuring the "out" power.