Q.Rose of Sharon bush died
I have had it for at least 10 years and it was always beautiful and thick. Last year there wasn’t as many flowers or leaves; for that matter, it never looked very full. This year there is nothing! There are no leaves ever….just the wooden stems, as if we poisoned it. Any idea what could have caused this? It is on the west side of our house, and it was a beautiful bush.

Rose Of Sharon does not have a terribly long life span.
The long cold winter that nearly the entire United States suffered may also have contributed to the loss of your plant.
I try to remember that a loss in the garden makes for new opportunities.
https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/rose-of-sharon-bush.htm