Do you mean it won't roll down at all, or won't auto roll down?
If it won't roll down at all - I had the same issue in my 09. It urned out to be a back connection in the printed circuit board that the switches are mounted on. I checked the switch and took it apart and checked the contacts, all OK.
Then I tested the window motor by sending power to it directly and it rolled up and down.
I went back to the switch assembly and checked the circuits with a meter. I found a bad circuit and jumped it with a wire so I could get it rolling right away and it worked and still is, but probably best to buy a new circuit board.