It’s a big problem. It is possible that your water heater doesn’t heat up water. It could be due to the heating element or thermostat.
If you want to check the water heater, you will first must turn off the breaker. Then you are safe from electrical shock. Remove the covers at the reset button . Press that red reset button. The sound of a click should be heard. Make use of an electric voltage tester to test the temperature of the thermostat. Make sure that the wires are connected between the thermostat and elements. Since the thermostat is both of the elements, the element must be able to read between 12-13 Ohms.
Reset the lower and the upper thermostats if you notice that the wire is spinning. While you are there examine for burn areas or leaks in the vicinity of your water heater. They can indicate more serious issues. Turn on the breaker and check the power. The thermostats should be adjusted: upper to 120 and lower to 122(slightly higher).
It is possible to replace every component if any of them is faulty. Your water heater will start running again after having completed the steps. It’s recommended to contact a specialist if it’s not enough to fix the problem.