Just leave it alone until spring. When the forsythia starts to bloom is when you should do your spring pruning. Take off anything that looks dead or dried up. When you prune look at the center of the cane. If it is tan or brown and looks dry it is dead. If it is greenish white and looks moist it is still alive. In your cold zone you may have to prune it very low. Don't worry, it will come back. Once it is pruned give it some fertilizer and watch it grow and bloom! Take lots of pictures and maybe we can help you identify it.
