Background image themes not display

I have tried changing my theme, background image from various locations, colors, resolution....nothing works. What has happened is that I can no longer view any image I choose to set as my background, except in the "preview" screen. My desktop will only change to different solid colors. I have the Windows Vista color schemes selected and I have tried to compare what I have set to what my child has and cannot come up with any differences.OS -windos vists



Can ANYONE help?!?