Significant hair loss and premature greying of hair at your young age needs to be addressed immediately. In hair loss prevention is always better than cure. There may be many reasons why you are losing hair. It can be due to hormonal changes, lifestyle, diet, or related to stress or smoking. Some people also have vitamin or thyroid dysfunction that could be the cause.
change your diet to include plenty of fruits and vegetables and protein. sleep well and drink plenty of water. Use a good ph balanced shampoo. In spite of these changes if hair loss persists see a dermatologist