Hello Ravi I suggest you to visit for a consultation.A good cosmetic Dentist can get the cause for yellowness it might be due to bleeding gums as well.yellow teeth might be from birth if you wish to lighten shade and get bright smile kindly get done laser whitening treatment.

The colour as you mentioned yellow could be due to either too much of plaque deposits or the colour of your teeth are naturally yellow.

well u can go fr bleaching...u can take home as well as office bleaching

There can be two types of yellow stains of the teeth. Extrinsic and intrinsic. The extrinsic stains are due to hard deposits of Calculus On The Teeth which are formed from the plaque  but cannot be removed by tooth brushing and will require tooth cleaning by a procedure called as scaling. This procedure does not lighten up the natural shade of your teeth. Intrinsic stains are imbibed in the chemical structure of the tooth and will require procedures like bleaching or laminates for their correction. The best treatment options for you can be delineated only after a proper clinical examination so you should plan for a visit to the dentist as soon as possible. Regards.