private void btnOpen_Click(object sender, RoutedEventArgs e)
{
Microsoft.Win32.OpenFileDialog ofd = new Microsoft.Win32.OpenFileDialog();
ofd.Filter = "Video (*.wmv)|*.wmv|Audio(*.mp3)|*.mp3";
if (ofd.ShowDialog() == true)
{
MediaEL.Source = new Uri(ofd.FileName);
btnPlay.IsEnabled = true;
}
}