Depending on the age and type of your water heater, there are a couple of reasons you don’t have enough hot water:
1. Electric water heaters commonly have two heating elements, one on top and one on bottom. Either of these elements can stop working. If the bottom element goes out, only the top portion of the water heater is being heated. If the top element goes out, there will not be any hot water.
2. There is a reset button that could have been tripped, causing the water heater to stop working. If that reset button has tripped, that is an indicator that something is wrong.