Private Sub btn_save_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles btn_save.Click
        My.Computer.FileSystem.WriteAllText("C:/mytext.txt", TextBox1.Text, _
        False)
 
    End Sub
 
    Private Sub btn_read_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles btn_read.Click
        TextBox1.Text = My.Computer.FileSystem.ReadAllText("C:/mytext.txt")
 
    End Sub