This is all my fault, as I was not paying attention when I went into the registry editor to try to fix something else. I was not intending to mess with wallpaper. Instead, I changed a value that made it so now I cannot change my wallpapers in Windows 7.
What I did was:
Navigated to HKEY_CURRENT_USERS\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop
Went to NoChangingWallpaper REG_DWORD. I don't remember what the original value was, but I changed it to 0x00000001 (1).
Ever since then, the wallpaper on my desktop cannot be changed.
I will appreciate input to get me back on track so that I can change to any wallpaper at any time.
Windows 7 Professional, 64 bit