You need ultrasonic scaling and polishing by a reputed dentist
. It will bring back natural color of your teeth without any severe damage to teeth or gums. If you wish for whiter teeth, ask for teeth bleaching
(chemical or laser
). Please do not use any home remedies like baking soda ,lemon drops, salt in oil, charcoal rub etc. You will only damage the teeth and gums which can also results in severe teeth sensitivity along with future problems.