What will happen if i will the remove the reset bottom sir?

your elements are burned out,be care ful when resetting if they are blown then you could send electricity through the water pipes,call a plumber or replace them yourself,turn off breakers,drain all water,unscrew the 4 screws that hold each element in and slide them out,dont damage or turn anything on the reset or connectors,take them to a parts store and buy two of them,they are about 25 bucks a piece

Two-element water heater is 240Volts.
No hot water means: ECO reset button tripped, upper element bad, upper thermostat bad, or 240Volts is not reaching water heater.
Circuit breaker can be delivering power on one leg of the 240V circuit, so water heater appears to have electricity but is only receiving 120V.
Test for 240volts across top two screws on upper thermostat.
Look for loose wires and burned connections.
Push in reset button real hard.
Replace both upper and lower thermostats.
Remove wires and test upper element for continuity.

Open following links for do-it-yourself troubleshoot walk-thru:
http://waterheatertimer.org/B220C.html
http://waterheatertimer.org/How-to-replace-thermostat-on-electric-water-heater.html
http://waterheatertimer.org/How-to-troubleshoot-electric-water-heater.html
http://waterheatertimer.org/Test-electricity-to-water-heater.html

You can open the top up again. I would not turn the temp higher than 130 degrees, maximum. However, there should be above the thermostat a red button. This is where the power wires connect to the thermostats and heating elements. Sometimes this button needs to be reset, press it and discern if you hear a click sound. This means that the high temperature safety switch has tripped open and you had to manually "reset" it. There are two thermostats by the way. The water heater usually works this way. There are two thermostats and two heaters. The upper tank heater turns on first and it heats the top half of the tank. Then when the thermostat above is satisfied it then allows the bottom heater to come on and heat the bottom half of the tank. You might want to set the bottom heater thermostat as well. This is made this way because it is actually faster and more efficient to heat the top half first and the bottom half secondly. Try this first with the reset button. We could check voltages, but that requires a level of knowledge and safety that I am not sure that you are comfortable with. Pictures of the upper and lower thermostats and connections will help if the "reset" does not do the trick. By the way, not meaning or implying anything, but did you move the thermostat in the right direction? Sometimes the dials can be confusing.

The reset button is set up to open the circuit if excess current is drawn by a failed Element. It works by getting hot and switching off due to current above its rating. The burnt wiring more llikely happened over a period of time because of a resistive joint in the block getting hot due to the high current that water heaters consume. It seems that the element has failed if the reset button does not get the system working.

There are two access panels on the heater, remove screws to access it. They cover the upper thermostat and element and the bottom covers the bottom thermostat and element.
The top thermostat is the main one that has a reset button along with a dial to turn up the heat for the top element. A white plastic knob that you can use a flat head screw driver to turn to adjust.
Also you have one on the bottom to turn to adjust the heat on the bottom.

This is how you adjust thermostat's to increase to a hotter setting.

1-First check for power to water heater and remove acces panels on heater to check power at thermostats. Thermostats have a reset button on them that trip and can be pressed to reset.

2- If none of the above have changed any thing and you have power you may have elements gone bad.

If an element is gone at top you will get scalding hot water then go to cold.

If an element on the bottom is gone you will get luke warm water then will get cold.

Willard when you say it throws the reset button,do you mean the breaker on your fuse box of your home?
If you mean that then yes it could be a bad element.The bottom element takes all the abuse on a electric hot water heater. They can short out,and need to be replaced.

if your blowing hoses , your getting too much preasure . for an ondemand heater to work correctly it needs to be insalled into a system with a recirculation line [it's basicaly a loop, so the water is always flowing].

If you don't have current, 0v from terminal to terminal, then you don't have voltage to the elements. Replace the thermostat but check that you have 220v to the thermostat. It is possible that your breakers to the unit are either bad or tripped.

i guess it is electric ,check bottom element reset button .remove bottom cover with power off look for a button on bottom thermostat or limit if find push it to reset ,,then set the thermostats , set top to desired temp and the bottom at least 10 degrees more ex. top 130 bottom 140 this might prevent problem reoccurring if this not problem bottom element could be burned out.replace ele