How to active the ads in candy crush?

There is no way of forcing adverts to appear in your game @abha_choudhary12345 As with every feature of Candy Crush you either have adverts or you do not. If you don't currently have adverts in your game all you can do is wait and hope that they appear in your game at sometime. Waiting doesn't mean you will get to see them though as you may never get adverts.

If you have ever purchased a booster package for your game you will never get adverts in your game.