I have two callophylums planted about 12 foot apart in great shade (sun comes in from West). They are about 12 years old and so big. However, we had bad cold weather (never been that cold before) and wind off the lake. Now one tree looks dead. All the leaves are brown and 80% of the leaves have dropped. The second tree looks 90% good with green leaves and just a few dead leaves mixed in. Anything I can do to the 'dead' one?
If the stems are still alive, they will regrow their leaves. I would give them a month, and if you do not see growth by then, they are most likely dead. These articles will help you as well: https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm