Why 3 lamps and a hood in a bathroom do not work?
First you need to check the wires in the switch, if the core that goes to the bathroom is normally clamped. If everything is fine, we check whether the switch works, that is, turn on the key and watch with an indicator screwdriver or with a multimeter whether the voltage appears on the "output" terminal of the switch. If it does not appear, replace the switch (or apply voltage to the wire “directly” bypassing the switch button.
If the switch is working, then check how things are with the lamps and the hood, you need to check whether their lampholders have both PHASE and ZERO when the switch is on. If something is missing, look for the problem in the junction boxes.