Sorry for what will likely be a long question! It all started with a bathroom light that would not turn on, even though the bulb was good. I decided to get my multimeter and see if the switch was sending any current but first wanted to test it on a receptacle that I knew worked (a GFCI outlet in the bathroom). I made a rookie mistake with the setting on my multimeter and when I put the wires in the receptacle, it tripped the circuit, popped and made a puff of smoke (thankfully no damage to the multimeter). The GFCI would not reset so I figured it was fried and I replaced it with a new one.
My second mistake was disconnecting the wires from the old one and not tagging which ones were the line wires and which ones were the load wires (3 cables come into the box, one goes straight to the receptacle, the other two are connected with wire caps and then go to the outlet). After trying both sets of wires, I found out that now there is no current at all coming into the box from any of the wires. After testing further, I found out that none of the bathroom receptacles in the house are working - one additional in the master bath, one across the house in another bath and one across the house and downstairs in a third bath. I don't understand this at all because all of the bathroom lights work and it seems strange to me that all bathroom receptacles would be on the same circuit when they are so far apart...why wouldn't a bathroom receptacle be on the same circuit as that bathroom's light?
Since there is no current going into the GFCI outlet, the problem must be upstream but I don't know where to look to find it. Yes, I've checked all the breakers and all are on (and nothing to indicate a separate circuit for bathroom outlets). I read a similar situation that turned out to be a faulty light switch in another room that was not sending current on the load wires. Without a wiring diagram, and apart from pulling all the wall plates in the house, what is the most logical plan of attack to figure out where the problem is?
EDIT: found it. Stupid user error. It turned out that the bathroom GFCI receptacles are on a different circuit from the rest of the bathroom and it never fully reset. After simply cycling the breaker, all is well. On the bright side, I did find an outdoor GFCI receptacle that was faulty and replaced it as well :)