I can't sync my controler

If your Xbox controller don't light no more it could be 2 things not having battery or it could be broken. If it was the battery (you should put some new ones)and the Xbox button lights up and it still doesn't sync, all you have to do is press the little tiny button on the left side of the controller, then on your Xbox press the sync button near the USB slots on the Xbox elite slim, if you have the arcade edition or the Xbox elite is next to the memory card slots. If you did this right it should work