Can hair regrow after the follicles die from the sun?

Part of my scalp was exposed to the sun, so that the follicles are dead. At the moment, I do not know the sun can kill your follicles. Now that I’m aware, I have kept out of the sun and growing my hair longer to cover my scalp more. I was looking for a new follicle growth, but my hair seems to be increasingly sottile.Non always grow back the hair from follicles that have been damaged by the sun?