Let the page load completely and wait a couple seconds as some operating systems load the song last.
If song does not start, first try refreshing the page (F5)
Sometimes just shutting your computer down and restarting will resume the music player
If there still is no music, here are a couple things to check in your Windows Media Player
Open your Windows Media Player (Start, All Programs, Windows Media Player)
Click Tools, then Options
Then File Types (On some it is formats)
Click Select All, then Apply, and OK
If that doesn't work your player is most likely outdated or you have missed some player updates.
Update your Windows Media Player here