text: how do i undo a split screen? there are three vertical lines on my desktop, and the background is solid blue.  the wallpaper is gone.  my aunt said she clicked on a rectangle on the desktop before this happened.   i want my wallpaper back.  how do i do this? right click on the mouse on you're desk top scroll to properties then select your wall paper on the list, for the bars you might have a bad moniter or it might have something to do with the wallpaper. if you have a crap comuter aka mac then it might be different i don't know i have a dell