Goto the public swimming pool, boil some water and wash, get a room at a motel/hotel, or call some friend & ask if you can use their shower.
You can't fix the problem, because it is likely that the access to the mechanical/HWT room is lock.
If you have access to the HWT, then check the breaker panel to make sure the power is on (electric HWT).
Or, check the pilot light to see if it out (gas HWT). Re light the pilot with start nob at pilot position, and it may take a minute or 2 at depressing the start button to flush the line with gas. Push electronic igniter rapidly several times to ignite the pilot flame(if it have an electronic igniter), or use a lighter to light the pilot if it have a manual starter.
Then turn the start button to on to start the burner after letting the pilot burn for 2 minutes.
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Check the flame to see if there is an even flame (steady motion & formation), make sure the flame is blue & no hint of yellowing.
The burner may need to be service, igniter may need to be replace, or thermocouple needed to be replace.
Oops, almost forgot, back track the gas line from HWT to the meter & make sure all gas cock/valve are on (on is parallel to the piping).