Hi..black patches over the face can be due to many reasons so you need to consult a dermatologist who will examine and tell you the exact cause of pigmentation. Many treatments in the form of creams and chemical peel are available which gives wonderful results in facial pigmentation, You have to consult a dermatologist for the same. But the most important thing is to start a good sunscreen immediately depending on skin type in morning 15 to 20 mins daily before stepping out in Sun.