Q.rose of sharon hibiscus tree
8 year old rose of sharon hibiscus tree is severely damaged from severe winter here in the east…dead limbs on half of the tree. Also, the trunk of the tree is starting to split. What can I do to save the tree? Any suggestions would be appreciated. Thank You

Really, the best you can do is to reinforce the split with a wrap to keep it from splitting further and remove any dead branches. In cases like this, you just have to give the plant time to heal.
You may find this article helpful:
https://www.gardeningknowhow.com/ornamental/trees/tgen/winter-damaged-trees-shrubs.htm