Q.hibiscus tree has no leaves
My tree is a hibiscus syriacus – double pink – had about 3 years, but this year it has no leaves. Can it be recovered or is it dead?
First, determine if the branches are dead. Try bending them; if they snap apart and are brown inside, they're dead. If they bend, they're still alive. If you find dead branches, you can go ahead and prune them back to live growth. The syriacus should be hardy in your area, but you never know, it sounds like it was damaged by severe weather. Check the info in these growing tips: https://www.gardeningknowhow.com/ornamental/shrubs/rose-of-sharon/rose-of-sharon-bush.htm
Pay attention to the pruning information. Continue to give it the best of care, and if it can recover it will. It may take 2 or 3 years.