All My Music Is Gone!?

We reinstalled windows and pretty much wiped out our hard drive recently. Before we did that we bought a small portable hard drive so that we could save important doents and files. I made a playlist of all my music and transferred it onto the hard drive and now when i try and open it with windows media player it wont open. It was saved as a "wpl" file. Is there any way to change it to a usable file type (such as wma or mp3) so that I can use the music or is it pretty much all lost. Any suggestions help.