Prova con questo:
codice:
Private Declare Function SystemParametersInfo Lib "user32" _
Alias "SystemParametersInfoA" ( _
ByVal uAction As Long, _
ByVal uParam As Long, _
ByRef lpvParam As Any, _
ByVal fuWinIni As Long) _
As Long
Const SPI_SETDESKWALLPAPER As Long = 20&
Const SPIF_UPDATEINIFILE As Long = &H1&
Function SetWallpaperBitmap(sBmpFile As String) As Boolean
Dim lRet As Long
lRet = SystemParametersInfo(SPI_SETDESKWALLPAPER, _
0&, _
ByVal sBmpFile, _
SPIF_UPDATEINIFILE)
SetWallpaperBitmap = (lRet <> 0)
End Function
'Per richiamarla:
SetWallpaperBitmap percorsodelfile