Private Function CorrectUsernamePassword() As Boolean
    Dim UserPasFile As New StreamReader("UsernamePassword.txt", False)
    Do Until UserPasFile.EndOfStream
        Dim Line As String = UserPasFile.ReadLine()
        If Line <> "" Then
            Dim CommaIndex As Byte = Line.IndexOf(",")
            If CommaIndex >= 0 Then
                If Line.Substring(0, CommaIndex) = txtUsernameLog.Text And Line.Substring(CommaIndex + 1, Line.Length - (CommaIndex + 1)) = Password Then
                    Return True
                End If
            End If
        End If
    Loop
    UserPasFile.Close()
    Return False
End Function
Private Sub RemoveDefaultData(ByRef TxtBoxChanged As TextBox, DefaultTxt As String)
    If TxtBoxChanged.Text = DefaultTxt Then
        TxtBoxChanged.Text = ""
    End If
End Sub
Private Sub AddDefaultData(ByRef TxtBoxChanged As TextBox, DefaultTxt As String)
    If TxtBoxChanged.Text = "" Then
        TxtBoxChanged.Text = DefaultTxt
    End If
End Sub