Apply neelakant hair oil regularly it will help to reduce greying of hairs. Ayurveda treatment like Nasya , shirolepa,  shirodhara also help in  managing early greying

Hello there...I can understand your concern. Calm yourself first. Stress will increase your problem. White hair occurs due to 2 main reasons. One is hereditary. If it's due to hereditary, then no treatment will help it. You have learn to live with it. Secondly it can be due to vitamin deficiency. In such a case, supplementing with the required vitamins might help the cause. But it will take about 4 to 6 months to see the treatment. You must understand that even with vitamins the result is very poor. So learn to live with it. Try natural hair dyes also if you are desperate for black hair. Kindly consult a dermatologist. They will examine you and then treat accordingly.