First access the back of the water heater, there is an over temp switch that may have tripped. Search the model # of your tank, you'll be able to find a manual that shows the switch and layout. The switch and electric heating element connections maybe behind a metal cover that you'll have to remove. Then you can get to the switch and reset it. Just have to push it in. If that doesn't fix your problem you'll need to check for voltage at the element with a meter. If voltage is present then you should check the element itself with a meter, ohms. Not sure what access you have to back of tank but it may have to be removed to pull the heating element out the back if it needs to be replaced.
Ours stopped working on electric but lucky me I just had to reset the ECO (over temp switch). That was a year ago and it has been working fine on electric since then. As a note, if you have 'motoraid' (engine heat is used to heat the water) then don't turn on the water heater right after traveling, the water may already be too hot. Some say that shouldn't happen but that's the only time ours failed. Since then we use some of the hot water before turning on the electric heat.
Hank & Lynda
2003 Winnebago Adventurer 35U