You can put your sunglasses into warm water for a few minutes. And try to remove the stickiness with a piece of clean cloth. If you can't remove them in this way, you can put some soaps and rub them with a piece of clean cloth gently. And then rinse the soaps. If the lenses are made by plastic and the stickiness are hard too. You'd better take your sunglasses to an optical store. The optician can fix this for you. If he or she can't, you may need to buy a pair of new sunglasses.