We lost all of our water pressure the pressure tank is registering 0 the hot water tank should be full so is it the pressure tank or well pump?

We need much more info. Is there power to the pressure switch? Is the pressure switch working? Do you have a low pressure cut off on the pressure switch? (little lever on the side that you lift and hold until the pressure comes up far enough that things will work automatically) If not, is there power to the pump? What is the current draw when the pump is running? What should the current draw be? Is the pump short cycling? Almost certainly the hot water heater has nothing to do with this.

EPMiller