As long as it was not a heavy frost they should re-grow from underground. Use newspaper of fleece if frost is forecast again.

Cover the foliage by drawing soil up round it. Keep doing that till all danger of frost has passed.

Logged onto this site hoping to find the answer to this as well. My potato tops have wilted slightly because of the sharpish frost a couple of nights ago. I had earthed them up the previous week when a frost was predicted but got caught out by this last frost. Will earth them up if more frost forecast.