I can't change my wallpaper and I can't put any files on my desktop. Also my right-click menu changed from the normal one to the one in the image.
Try typing this in a terminal:
You can change the desktop wallpaper from this window.
And uncheck the box "Show menus provided by window managers when desktop is clicked" found under the "Advanced" tab.
Then you should be able to right click on the desktop and get the menu to bring up the preferences window that allows you to change the wallpaper anytime.