Plumbing Questions? Ask a Plumbing Expert.
First check your breaker and make sure it has not tripped. If it has not tripped, remove the top cover on the water heater (make sure you shut the power off to heater first) inside the top cover will be an red button, push that and see if that has tripped.
If those 2 are ok, we can trouble shot the heater if you have an multi meter to check volts and ohms?