I had pimples on my right cheek, they have gone but have left dark spots on my skin.its been almost two yrs.they haven't faded away. why so?

Can bleach: Postinflammatory pigmentation does eventually go away after acne, but you may be able in the meantime to bleach these with a quinone bleach. Good luck.

Hyperpigmentation: Hyperpigmentation (darkening of the skin) is a common reaction to inflammation in many people. The darker the skin tone is naturally, the more likely hyperpigmentation will develop from inflammation. Prescription hydroquinonne (4%) is an effective treatment for hyperpigmentation.