Hello there! Thank-you for sharing your picture - a professional clean would be a great starting point for you as it is very likely that there is extrinsic stain which can be removed very simply by polishing. This is a simple, inexpensive and very conservative option.If this makes little difference, it may be that the stain or discolouration is coming from within (we call this intrinsic discolouration) and this can sometimes happen as a result of trauma where the nerve tissue inside the tooth becomes damaged. Some tests and X-rays may be required to ensure that the nerve tissue is healthy before any other treatment like whitening or veneers would be considered but because veneers are not reversible, they would not be our first option for treating discolouration.I hope that this helps answer your query.