I installed variety on ubuntu 14.04 and customize login screen support option to set variety wallpaper set as login screen background. i copied my wallpaper directory into ~/Pictures directory and set access permission as 777 to both directory and pictures. after that wallpaper showed up correctly on login screen and everything works well.
after few days login screen didn't change according to the desktop wallpaper and it turned into ash color and when i open unity tweak tool's login settings It looks like this.
how do i reset these settings and solve this problem. thanks in advance.