How do you reverse vitaligo?

You don't. In vitiligo, you loose the melanocytes (pigment cells) in your skin due to some cause. Once lost, it is nearly impossible to regenerate these pigment cells. This results in a loss of pigmentation to affected areas of the skin (remember michael jackson?). The treatments range from "fake and bake" to using topicals to try and grow more pigment cells. See a dermatologist for more definitive help.