My napster music will not play in Windows Media Player or Itunes.?

I recently upgraded my computer and I used to have a Napster Subscription to purchase my music. When I tried to play the wma files from Napster on my new computer it will not play. I am confused as to why this is because it says (WMA). So can someone help me get my old files to work. I do not want to purchase another 2000 songs, its just way to much. Thanks.