I am a dark skin person female and the skin around my genital area is white. what is the cause of that and how can i fix it. ?

White spot: See your dermatologist for an appropriate diagnosis. Vitiligo is a condition where there is loss of melanocytes and the skin gets very white. Often it starts around body orifices. Your doctor can look at your skin with a woods light and see if there are lighter spots developing anywhere else. Treatment depends on what the diagnosis is.

Vitiliggo or LSA: Lichen sclerosus et atrophicus are usually whitish skin elevations and may respond to steroid cream. Can resolve spontaneosly in young , but, not in mature women. Vitiligo is a condition of skin depigmentation. It is quite benign and does not respond to any treatment. Suggest you consult with a gynecologist.