Thyme is a pretty robust hardy perennial sub shrub which is expected to last several years. Leave them alone and they'll very likely green up. Once they've grown back you can shear them over lightly to keep them neat.

If thyme survives in my zone 3 with no special care it will surely survive your zone 7 conditions. Leave them alone and they'll come back. Thyme is pretty hard to kill. Some green should tell you it's ok. If it were dead there'd only be twigs

My experience(Z6) is that small patches of green survive, while most of the plant dies. I prefer a fresh, new, green plant each spring to the patchy look of a half-dead one.

My thyme plant was barren 2 months ago and its completely green now. The plant is 3 years old.

Here in NH zone 5, most thymes do well for me. I have creeping thymes that just keep making bigger and bigger mounds. If what you have is a creeping thyme, you might want to cut the plant back at least half way to encourage good growth. It doesn't need any special care in winter.