Customer stated that he had reset the bathroom gfi. This then caused and the bedroom, hall bathroom, and guest bedrooms to lose power. We did a visual inspection and informed the customer that a troubleshoot would have to be done. Customer agreed. We found that a safety breaker, which was located in the Sub panel, was in the tripped position. When turned on, the gfi in the bathroom would trip but the bedrooms regained power. When the gfi was reset, it would trip the breaker in the main panel for the gfi and the breaker in the sub panel. This let us know that it was back-fed. This means that there are two sources of power going to the circuits. We capped of the load side, which was being fed off of another breaker, in the bathroom gfi outlet. We then checked outlets and switches for proper voltage.