To reset your wallpaper in batch, and have the change immediately reflected, download, unzip it, and move SetWallPaper.exe to a folder in your path.

When you type SetWallpaper /?, the following help is displayed:

                              Set Wallpaper version 1.10                              Sets the desktop wallpaper and updates the current user profile.                              Syntax:   SetWallpaper.exe \[/D:C|T|S\] filename.bmp|/R                              Examples: SetWallpaper.exe C:\Downloads\Pamela.bmp                                        SetWallpaper.exe /D:T C:\Downloads\Carmen.bmp                                        SetWallpaper.exe /r                              The last parameter should be either the bitmap filename or /R                              An argument of /R will remove the desktop wallpaper.                              An argument of /D: allows you to display the image Centered, Tiled or                              Stretched.                              An argument of /? or -? displays this syntax and always returns 1.                              A successful completion will return 0.                              Copyright 1999-2000 Marty List