I have a water heater that has not been used for a couple of months with water in it and turned off at the breaker. I just tried to turn it back on and it won’t heat up. Is it shot from non use or what can go wrong with it from non use?
Non use should not be the problem unless it already had some problem when you shut it off and the period of inactivity caused complete failure. The problem is most likely very simple to cure but you have to check both thermostats and elements to see if they are bad or need adjustmetn. Without the proper tools and experience you may not be able to do it yourself and should call a plumber.