When I complete a task it give no reward iv been waiting for days

I presume you mean rewards for installing apps? Those are handled by a third party, and you need to contact them directly. Has nothing to do with Social Point.

As Bruce said , you will have to contact the ad company
you can look here for more info
https://forums.socialpointgames.com/topic/941/all-about-monsterwood-it-may-not-be-bugged