I see you didn't pick up on my little hint to tell us what species of trees they are.
All I can do is guess. If they are tropical or subtropical trees they are likely dead already. If they are temperate trees used to cold weather then they may be ok. A couple of things you can check. The small branches should remain flexible throughout the winter and when a little bark is scratched away it should be moist underneath. If you run across branches that are totally dry and brittle then those branches have died. Don't throw anything out until July. Even if the tops have died back they may sprout from low on the trunk.
Tony