Can you turn back light skinned if you turn light brown and you a black person?

There is a disease/condition called "vitiligo" that usually shows up as a patchy loss of pigmentation.

If that's not what you're talking about, I don't understand the question. As nearly as I can figure out, you're claiming to be a "light skinned black person" who "turned light brown", which doesn't make a great deal of sense to me.