We have a 50 gallon hot water tank and we have changed both elements and the thermostat and it still won't give any hot water. We also checked to make sure we had power going to everything and we checked the circuit breaker and everything has power but still no hot water?

we also checked to make sure we had power going to everything

How are you doing that? Are you using a meter?

Note that the top thermostat unit is both a thermostat for the top heating element and a over temperature safety device (with reset button).

The bottom element does not come on until the top thermostat is satisfied.

Am curious how you got the findings as well, I usually start at the top and work my way down with a meter, through the reset button, thermostat and down.
For Water Heaters I like using an Amprobe and a Meter. If the Element has power and has shows the load of the element, it is good, little or no current, it is bad.
Verify Thermostat(s) doesn't need to be adjusted.