To play a wave file, place a MediaElement control in the page or window:

...
<Border Margin="5" BorderThickness="2" BorderBrush="Black">
  <MediaElement x:Name="player" LoadedBehavior="Manual"/>
</Border>
<Button Name="btnPlay" Content="Play" Width="75" Click="btnPlay_Click"/>
<Button Name="btnStop" Content="Stop" Width="75" Click="btnStop_Click"/>
<Slider Name="sliderVolume" Height="23" Minimum="0" Maximum="1.0" Value="1.0" Width="100" ValueChanged="sliderVolume_ValueChanged" />
...

To programmatically control de Media Player:

using System.Windows.Media;
using System.Windows.Media.Imaging;
...
private void btnPlay_Click(object sender, System.Windows.RoutedEventArgs e)
{
   player.Source = new Uri(@"C:\TEMP\SoundApplication\demosoundclip.wav");
   player.Play();
}   
private void btnStop_Click(object sender, System.Windows.RoutedEventArgs e)
{
   player.Stop();
}
private void sliderVolume_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
   if (player != null)
   {
       player.Volume = sliderVolume.Value;
   }
}