Has there always been water in the tank? And, has the switch on the tank always been on?
I ask this, as I fried my heater element by inadvertently having it on with an empty tank. This is one thing that prompted me to put a switch inside with an indicator lamp for when it is on.
Other than that, I would just suggest checking the switch, maybe operating it a time or two, and check the connections on the element. If all looks good, with the switch on, check the voltage on the connections of the element, and if there is 120V there, the element is likely not working. If no voltage there, it must be with something ahead of there, which really can only be the switch, or breaker or their connections.
2017 Escape 5.0 TA (someday soon, I hope
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln