YC 1 wrote:
The won't reset if they do not have 110 volts going into them. Be sure your 110 volt path is working. For example, are other outlets working? Have you checked your AC panel breakers.
He said the "breaker", meaning in the "breaker" Panel. It's not a problem with the outlets not resetting, it's the breaker not resetting.
Yes, the problem can be in any of the outlets. You can try disconnecting the black wire at the GFCI breaker in the panel. The breaker should then reset. If it does, you have to disconnect each outlet individually until you can reset the breaker. That is the guilty outlet and should be replaced.
I would give my first attention to the water heater. Possible the heating element is grounded. Disconnect that from the outlet and try to reset the breaker.
You may want to consider an outlet that possibly was exposed to moisture.
You could also use a hair dryer to dry out the outlets. Might work.