Massage the scalp with ghee regularly. Drink carrot juice. Drink lot of water. Eat health balanced diet. Eat fresh fruits, vegetables, pulses and cereals.
Lemon juice mixed with Gooseberry (Amla) powder applied on the scalp for 15 days helps white hair to turn black.
Half cup of curd mixed with a pinch of black pepper (kali mirch) powder and spoon of lemon juice applied for 15 minutes before taking bath.