Importa il namespace System.Runtime.InteropServices

e aggiungi il riferimento alla funzione mciSendString di winmm
codice:
    <DllImport("winmm.dll", SetLastError:=False, ExactSpelling:=True)> _
    Public Shared Function mciSendString(ByVal lpstrCommand As String, ByVal lpstrReturnString As String, ByVal uReturnLength As Integer, ByVal hwndCallback As Integer)
    End Function