Microsoft allows to re-acquire licenses for your CD ripped .WMA copy-protected files 8 times only. But when you have CDs, you can just re-rip songs again. There are many programs that you can use for that including freeware ExactAudioCopy. And if you use Windows Media Player, do not rip to DRM protected files, rip to MP3 files instead.

There is also a freeware application called unfuck.exe. It worked for many people. But it doesn't work for me saying: "Can't play the file". This error usually occurs when you don't have a valid license.