Woke up today and I have no hot water in my house I don't know where to start?

First, check all breakers, with no testers, you might try pushing in the red reset button on water heater. Volt meter will allow you to follow power in to the water heater, through thermal reset, then thermostat, then to element. If you have voltage to element, and no heat,likely bad element. Resistance test on element can determine open also.
I like to use voltmeter and ampprobe. If it has voltage, and not drawing current, it is Open. Good luck. Water heater will indicate voltage, if 220/240 then check the Double pole breakers, maybe 20 or 30 Amps.

Solobones99-; #1- go and check the breaker ,in the panel box, to see if it has tripped, if it has turn off (all way to left) to reset the breaker. IF you have screw in fuses. Unless you can see if the fuses that are for the tankare burnt out ,use one that is good to screw in to try. If you have a meter, set on a.c. volts, 250 volts touch one to each of the screws on the end of heat element ,if needle goes to the right, the element is got electricgoing to it.. now to check the element farther, turn off power to tank ,take one wire off end of element, touch propes to screw ends set meter to ohms, for conuinty of element. (BUT) that will not tell the truth as to if the element is blown or not. Hold one pprobe to one of the screws and other to the tank, make good contact to tank. IF needle don't move to right it's OK, the reason you do the way I just had you to is because water is a conductor of eletricy so if you don't do as I said even the meter will lie to you ,checkboth elements if OK put wire back on screw and tighten back down. Now if everything checked OK so far go to the thermostates by each eleament .IT willmost likely be the bottom, because it is the one that operates 85% of the time. INstall new ones and you should get hot water, Hook wires back same as you took them off:::: Turn power back on , you should have hot water in about 30 to45 min. GOOD LUCK::: IF I ha ve helped , rate me below F.B.E.