While I agree that it sounds like the water is not heating, I disagree with the advice that changing the element will fix the problem. No parts should be changed unless the part has been tested and actually found to be faulty. You will be wasting your money otherwise if you just put in a new element but that doesn't fix the problem. You need a test multimeter and need to know how to use it to fault find step by step. First checking for open circuits on wiring or element or thermostat etc. Then checking if power is actually getting to the element. If you don't have the test meter or fault finding experience then you will do yourself a favour by calling someone out to do it.
Lincoln Appliance NZ, January 2017