Need some Help and Advice!

Hello everyone I'm new to this site and new to electrical. I'm trying to help my father out with an electrical problem in his BATHROOM because he can't afford an electrician. There are 4 switches and 1 GFCI outlet. I believe all of the switches to be just SPST switches given there are only two wires hooked up to each switch and each switch only controls one thing. Only 1 switch in the bathroom is working and that controls the vanity light, the fan/light combo on the ceiling is not working and did work fine for a long time b4. I tried replacing all of the switches and the GFCI Outlet and still nothing at all. I'm guessing maybe a short in the wiring somewhere. The switch that is working has 2 black wires connected to the switch terminals and a ground with the 2 neutrals tied together with a wire nut. Could the bottom black wire be switched with 1 of the neutrals to provide an extra set of working wires?? Seems logical to me given that normally you have a black and a white wire hooked up to a switch and not two black wires. Please advise and thanks in advance!