Is the breaker for the water heater on?
Unless your water heater is fitted with a heat exchanger, that's the most obvious reason the water isn't getting hot. If that's not the problem--AND it's not a heat exchanger model, I suspect it's just time for a new heating element. Fortunately, heating elements are pretty much a "universal" part and easy to swap out. Just make sure the wattage is the same.If you DO have a heat exchanger, my guess is--the yard (correctly) bypassed the water heater when they winterized and overlooked putting it back online when they de-winterized. That's just a matter of disconnecting a couple of hoses from each other and reconnecting 'em to the water heater.