I got a dark scar on my face for using 10% benzoyl peroxide gel and 5% gel. and it does not fade. it looks like a dry burn. how can i treat it?

Hyper pigmentation : It sounds like you have an area of hyper pigmentation after inflammation. Some folks tend to do this more than others but there are options for treatment. Brown pigment can respond to lightening creams, IPL, or ablative laser treatments. Generally with lightening creams the pigment can return upon stopping. I lean more toward IPL or Laser. Sometimes it will improve on its own given time.