title: Playing a music file in the music library
body: <p>how do I play a song from the music library? I tried this:</p>
  
  <pre><code>private void click_AlarmSet(object sender, RoutedEventArgs e)
  {
      play();
  }  
  
  async private void play()
  {
      var openPicker = new Windows.Storage.Pickers.FileOpenPicker();
  
      openPicker.SuggestedStartLocation =Windows.Storage.Pickers.PickerLocationId.MusicLibrary;
      openPicker.FileTypeFilter.Add("toxic.mp3");
  
      var file = await openPicker.PickSingleFileAsync();
      var stream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read);
  
      sound.SetSource(stream, file.ContentType);
      sound.Play();
  }
  </code></pre>
  
  <p>here <code>sound</code> is my media element and "toxic.mp3" is the mp3 file I want to play, but the mp3 is not playing.</p>