My skin got burnt after alexandrite laser hair reduction. What can I do to reduce pain & get back my normal skin color? (Photo)

I am sorry to hear about your experience.  An Alexandrite (755 nm)LASER is better served on lighter skin patients (Fitzpatrick I and II).  Nd:YAG (1064nm) is better for skin of color.  You will have to use agents that reduce the pigmentation of the treated areas over time (hydroquinone or Kjoric acid) plus suncreeen (min SPF 50) to see any improvement.

I'm sorry this has happened. As stated previously, the was the wrong laser for your darker skin type. A 1064 YAG laser is the right one for you. I also can imagine why the operator continued to treat the entire leg. They should have recognized that the skin was not reacting properly. A derm or Plastic Surgeon is needed to evaluate you. Probably a form of Retin A and hydroquinone would be best to use, but you must be followed by a doctor.