Adding files to assets
You need to right click the Assets folder in Visual Studio and select Add existing item (you can’t just copy files into the folder in explorer)
Files That Were Packaged With Your App (Assets)
Windows.Storage.StorageFolder folder = Windows.ApplicationModel.Package.Current.InstalledLocation;
Windows.Storage.StorageFile file = await folder.GetFileAsync("Assets\\SomeFile.txt");
<MediaElement Name="audioplayer1" AutoPlay="False" Source = "Assets/audio_song.mp3" />
