The code below shows you how to start an application (in this case, notepad) using the Shell statement, and then close it again by sending it the WM_CLOSE message. Please note that not all applications pay an attention to this message! You will have to try it first.
Private Declare Function GetForegroundWindow Lib "user32" ()
As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA"
(ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any)
As Long
Private Const WM_CLOSE = &H10
Private lNotepadhWnd As Long
Private Sub cmdStartNotepad_Click()
Call Shell("notepad", vbNormalFocus)
DoEvents
lNotepadhWnd = GetForegroundWindow
End Sub
Private Sub cmdCloseNotepad_Click()
Call SendMessage(lNotepadhWnd, WM_CLOSE, 0, 0)
End Sub