Premature hair greying is a difficult problem to solve. I think you should at first check whether this problem is hereditary and secondly, you should immediately consult a good hair expert. Apart from this, you can try out an herbal hair oil rich in Amla, I have heard that Amla works well in preventing hair greying (From an article, I even read that “…amla is also great for the hair. It nourishes hair roots and is believed to prevent premature greying. Thus one often sees amla-based shampoos and oils.”). So until you visit a hair expect, you can try out Amla Herbal Hair oil. You can get the product at http://www.naturalplaza.com/