No hot water. hitting reset button starts it up but keeps tripping breaker

Try re setting all three its getting old, is the circulating pump ok if its not working the boiler will get to hot and shut down

Water heater has upper and lower elements. Only one t-stat. Check to see where tstat is set to. Turn down to lowest level. If breaker still resets then replace tstat. It is letting the water get to hot no matter what setting it's on. So water is getting so hot that it trips breaker.

It can be the breakers in your house or the reset button is malfunctioning

Check to see if there is a GFI outlet in the house or garage. Reset if tripped. My wife would trip the GFI in the garage when she used the hair dryer in upstairs bathroom.

Breaker could be bad.
Let's do a quick check and save you money.
Open top cover on water heater and push in red reset button that might be tripped.
If reset is tripped, water heater should turn ON.
If reset will not reset, then replace upper thermostat:
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
If reset is not tripped out, then it is OK, so test two top wires on upper thermostat.
Use cheap multimeter from home center, and set dial to 240-250-277 VAC.
Test across top two screws on upper thermostat to see if you have 240Volts.
To do full troubleshoot on ordinary tank electric water heater takes 30 minutes and multimeter
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html

If water heater is not receiving 240V, then the breaker is suspect, or a wire between breaker and water heater is loose.
See basic water heater circuit
http://waterheatertimer.org/240-v-water-heater-circuit.html

Now let's look at circuit breaker:
Mark suspect 240V breaker.
Identify all your breakers, and also mark another 240 Volt breaker that is same amperage as water heater 240V breaker.
Turn off main breaker.
Take front panel off breaker box.
The wires and lugs on main breaker are HOT, so stay away from that area.
http://waterheatertimer.org/See-inside-main-breaker-box.html
Suspect breaker has 2 wires coming from breaker.
See if one or both wires are loose, and then tighten.

If wires are tight, then move these wires to the other 240V breaker that is rated for same amps as water heater.
Now turn on main breaker.
Put ear against water heater tank to hear bubbly fizzing sound.
This will identify if circuit breaker is bad, or if water heater needs a full troubleshoot.
It is not a good idea to run two 240V appliances on same 240V circuit breaker, so you may have to decide one or the other appliance until you can replace breaker.
Instructions to replace circuit breaker:
http://waterheatertimer.org/How-to-replace-circuit-breaker.html

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Bad reset mechanism.

Shut off all power to water heater at breaker panel,remove side cover where thermostat is located. Test that there is no voltage at connections, with meter, to be 100% sure you shut off correct breaker. Thermostat should have a red button in middle to depress to reset if it's tripped.

replace the t stat

it usaly takes a few hours to heat up depending on water size check our breaker to see if it tripped out make sure all your wire connections are good u could take the front plate off and hit reset if you dont get hot water in a few hours ull probibly have to replace the trermostats and maby the elements its not hard to do good luck