Wallpaper Option Has Disappeared

view story

http://androidforums.com – I have list all options for wallpapers. When I long press the screen, the option has disappeared, and I now have a black background. I have gone into settings and tried to set it there, but though the wallpaper option is in it, it does not take, live or still. It happened when I installed the app Multipicture Live Wallpaper. I had all the options before it, but after I set a wallpaper in it, the option disappeared, and the screen stays black. I still have the icons, just a black background for a wallpaper. I have tried to restart the launcher (Apex), restoring the backup and rebooting the phon (General)