Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect([A1:C10], Target) Is Nothing Then
If Target(1) = "" Then
If MsgBox("Etes vous sûr? ", vbYesNo) <> vbYes Then
Application.EnableEvents = False
Application.Undo
Application.EnableEvents = True
End If
End If
End If
End Sub