There's really nothing you can do, it's most likely damage from the cold (sometimes covering isn't enough to prevent this). The plants themselves should recover, but they make look a bit ratty for a while and probably won't bloom this year if all the buds/flowers got frozen.
Yeah, that's right. There's nothing you can do except keep taking care of them and let them bounce back. I have lots of large azaleas and could not cover them, so some of them look pretty bad right now also. I think everyone lost something that was in bloom. I had just set out my herbs and my annual purchase of purple petunias and so far they look OK.