They can recover but it may take a while for them to leaf out. I would leave them alone (prune dead wood around late May or so) and simply maintain soil moisture and keep them well mulched. Not sure how holly or magnolia recover though; it is too warm here to have that problem.

luis pr.. Thank you for the information. I'm hoping they will recovery because the stem tissue appears very much alive. Once and a while, this far north, some hollies and magnolia granfilora will burn and defoliate in severe winters, but they recover completely.

I have had recently planted camellias killed to the ground by cold and then come back from the roots months later. I would leave it alone unless you need to fill in the place right away for aesthetic reasons.

I have the fall blooming variety "Snow Flurry" and it has proven to be very hardy here, with absolutely no problems of dieback or leaf burn. I've had it for about 10 years now and it always performs. A few hundred blooms are normally produced, and it blooms from mid-October into December, but the season may be short if the weather gets cold early. Then the remaining buds won't get a chance to open. But the vegetative growth is totally hardy. The only problem is keeping it sheared now and then so it doesn't overrun the area!

I also have 4 spring bloomers. Two each of "April Blush" and "April Dawn". They do fine. One of the Blush is about 10 years old and died almost to the ground in the severe winter of 2003-2004 (Jan 2004 was brutal!). I left it alone and in June of that year I finally saw a tiny green speck almost down to the ground on 2-inch-thick wood. Right now it's about 5 feet tall and 3.5 feet wide. It has about 60 buds and the first one opened today. So don't be too quick to give up, and cut back ONLY where you are sure the wood is dead (by scraping the bark - if there's any green at all, leave it alone).
Good luck!