The breaker that is mentioned is the accessory feed breaker and may be a smallish box with a red reset button on the front. If it is tripped or bad, none of your accessories would work, like horn, lights, VHF etc and I think you would have noticed that. So the main breaker is probably not the issue.
The switch at the helm may have a breaker. That would be the little buttons usually mounted in line with the switch. I can't be sure without seeing the dash panel.
The more likely issue is a bad pump or bad wiring. First step is to see if there is 12 volts at the pump feed (probably hard to access
) and then check the ground connections at the pump.