All of a sudden no hot water...
Does that mean:
1) you get water flowing from hotside of faucets but it is NOT HOT
OR
2) you get NO water flowing from hotside of faucets
1..water flows but is not hot....WH Tank Bypass Valve Open or Outside Shower not turned off using hot/cold knobs
OR electric is not heating water (See more info below***)
2---NO water flowing.....bad check valve in WH Tank HOT Outlet --stuck closed/stopping flow of water out of WH Tank
Just a guess cause you don't have much info as to brand/model of Water Heater OR 5th wheel posted.
***Suburban Water Heater Electric is a direct 120V AC circuit
AC from Circuit Breaker (Main AC Panel) to On/Off Switch to Set of T-stats to element
So check if the AC circuit breaker is tripped...turn it OFF then back on to be sure
Then check that you check if ON/Off Switch in outside compartment (lower left corner) got turned OFF...turn it on
Then check if HI temp T-stat is tripped...Push to Reset Cover above gas valve...Left side is for the 120V AC. If tripped you will feel it reset when your push in on button
Course it could be bad element (under the cover below gas vlave/burner tube)
And IF you have a fancy monitor/control panel inside RV that system probably uses a DC/AC Relay for the on/off switch on panel
Do you have a voltmeter and know how to use it?
If YES/YES
Set it to AC Voltage and start testing the AC circuit
Remove cover on t-stats and you can test for AC to/from the set of t-stats
AC from on/off switch comes in to top Hi Temp t-stat then to bottom t-stat then to element
Remove cover on element and test for AC to/thru element (black wire/hot---white wire/neutral)
Should fire up on Propane cause that is a completely separate system ---12V DC circuit & propane