Как узнать что воспроизведение завершено?

   Private Declare Function MSS Lib "winmm.dll" Alias "mciSendStringA" (ByVal lpstrCommand As String, ByVal lpstrReturnString As String, ByVal uReturnLength As Long, ByVal hwndCallback As Long) As Long
 
    Public Function PlayFile(ByVal strFileName As String) As Long     ' Воспроизведение внещнего файла
        Call StopPlay()
        Call MSS("OPEN " & strFileName & " ALIAS FIRST", vbNullString, 0&, 0&)
        PlayFile = MSS("PLAY FIRST", vbNullString, 0&, 0&)
    End Function
 
    Public Sub StopPlay()                                       ' Остановка внешнего файла
        Call MSS("STOP FIRST", vbNullString, 0&, 0&)
        Call MSS("CLOSE FIRST", vbNullString, 0&, 0&)
    End Sub

'Проигрывает фоновую музыку, которая сменяется
Public Class Плеер
    Dim n As Integer = 0
    'Dim Songs() As String = IO.Directory.GetFiles(Application.StartupPath, "*.mp3", IO.SearchOption.AllDirectories)
    Dim files As System.Collections.ObjectModel.ReadOnlyCollection(Of String) = My.Computer.FileSystem.GetFiles(Application.StartupPath, FileIO.SearchOption.SearchAllSubDirectories, "*.mp3")
    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        'WindowsMediaPlayer1.URL = Songs(n)
        WindowsMediaPlayer1.URL = files.Item(n)
    End Sub
    Private Sub Проверяет_состояние_плеера(ByVal sender As Object, ByVal e As AxWMPLib._WMPOCXEvents_PlayStateChangeEvent) Handles WindowsMediaPlayer1.PlayStateChange
        On Error Resume Next
        If e.newState = WMPLib.WMPPlayState.wmppsMediaEnded Then
            n += 1
            If files.Count = n Then
                n = 0
            End If
            'If Songs.Length = n Then
            '    n = 0
            'End If
            'WindowsMediaPlayer1.URL = Songs(n)
            WindowsMediaPlayer1.URL = files.Item(n)
            WindowsMediaPlayer1.Ctlcontrols.play()
        ElseIf e.newState = WMPLib.WMPPlayState.wmppsReady Then
            WindowsMediaPlayer1.Ctlcontrols.play()
        End If
    End Sub
End Class

Dim files As System.Collections.ObjectModel.ReadOnlyCollection(Of String) = My.Computer.FileSystem.GetFiles(Application.StartupPath, FileIO.SearchOption.SearchAllSubDirectories, "*.mp3")    
заменить на
 
Dim FoldD As New FolderBrowserDialog
            FoldD.Description = "Выберите папку с музыкальними файлами. В случае ошибки - действие ОТМЕНЯЕТСЯ!"
            If FoldD.ShowDialog = Windows.Forms.DialogResult.OK Then
                                   Try
                        Dim files As System.Collections.ObjectModel.ReadOnlyCollection(Of String) =  IO.Directory.GetFiles(FoldD.SelectedPath, "*.mp3", IO.SearchOption.AllDirectories)
                      
                    Catch ex As Exception
                    End Try

Dim  MusFon As Audio
 
    Private Sub PlayMusFon()
        Try : MusFon.Dispose() : Console.WriteLine("диспознули") : Catch ex As Exception : End Try
        MusFon = New Audio("data\Fon2.mp3")
        AddHandler MusFon.Ending, AddressOf MusFon_Ending
        MusFon.Volume = "-0800"
        MusFon.Play()
    End Sub
 
    Private Sub MusFon_Ending()
        PlayMusFon()
    End Sub

    Private Sub PlayMusFon()
        Try : MusFon.Dispose() : Console.WriteLine("диспознули") : Catch ex As Exception : End Try
        MusFon = New Audio("data\snd\fon\Fon2.mp3")
        '  AddHandler MusFon.Ending, AddressOf MusFon_Ending
        MusFon.Volume = "-0800"
        MusFon.Play()
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        PlayMusFon()
    End Sub

Imports System.Windows.Media
Public Class Form1
    Public WithEvents TMediaPlayer As New MediaPlayer
End Class