Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Integer)
    Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Integer
    Private Declare Function ShowWindow Lib "user32" (ByVal hwnd As Integer, ByVal nCmdShow As Integer) As Integer
    Private Const SW_HIDE = 0
    Private Const SW_SHOW = 5
 
    Private Sub Form1_Click(sender As Object, e As EventArgs) Handles Me.Click
        Dim h As Long
        h = FindWindow(vbNullString, "Form1")
        If h > 0 Then
            ShowWindow(h, SW_HIDE)
            Sleep(20000)
            ShowWindow(h, SW_SHOW)
        End If
    End Sub