If you look at the stems above the old leaf joints you should see new red buds just beginning to show. As these grow out the old leaves will be shed. Once there is lots of new growth trim off any twigs/branches that have died back to just above any new growth. I'm sure it will recover. This could also be the chance to rejuvenate it or train it into a new shape, I severely hacked my Bay (15 years old) last spring and it was full and leafy again by midsummer.