i messed up the air play setting for my itunes to my apple tv how do i fix it ?

im having a really hard time setting up my printer to my home wifi inorder to connect the scanner to my mac book wirelessly , i worked at it for a few days messing with settings and now i messed up the setting of my itunes being played through my apple tv. my printer isnt scanning and my itunes cant be played anymore i tried everything but i dont know what i did wrong .... please help me !!