You can check with Whirlpool but, don’t hold your breath. Call in someone and have them look at it. Usually both elements don’t go out and, you still get warm water or it warms and, you run out fast so, I don’t have an idea what could be the problem if, it just went out. A major control unit and, if so, this could cost you. Maybe better to put in a new unit if the heater is more the eight or, ten years old, rather then spending a lot of money to repair it and, then in a few years, replace it.

CALL A COMPANY THAT DEALS WITH WHIRLPOOL ASK THEM IF THE PARTS IS STILL UNDER ANY WARRANTY THEY CAN TELL WITH THE SERIAL NUMBER ON UNIT. YOU CAN ALSO VERIFY IF YOU CALL WHIRLPOOL.
LABOR AND SHIPPING COST NOT LIKELY COVERED

Most warranties are assigned to the original buyer and not transferable. Depending on the unit, the warranty may only be one year labor and at the most, 5 years parts. I would just fix it.