The answer to 'why is my water heater not working' is that there are several common causes, including a faulty thermostat, sediment buildup, or a malfunctioning heating element. Symptoms may include no hot water, lukewarm water, or strange noises coming from the tank.
Some potential solutions include checking the thermostat settings, flushing the tank to remove sediment, or replacing a broken heating element. However, if you are not comfortable troubleshooting or making repairs, it's best to call a professional HVAC technician to diagnose and fix the issue.