I have a 100 plus old Windows Media Audio files which are ‘protected’ by Digital Rights Management and therefore can’t be played by VLC or any other media players. (I’m a songwriter and some of these ‘protected’ files are actually my own songs!)
The WMA files can’t be converted to mp3 or any other type of file because apps such as Sound Converter and Audacity don’t recognise them.
There are a number of DRM removal apps available for Windows (they’re advertised as Freeware but it seems there are hidden costs).
If you still have a copy of Windows around, launch Windows Media Player and disable DRM - it's one thing I always did before adding my CD collection to the Music Folder. Or rather, don't apply the option when first setting up.
You could try downloading an old copy of XP and see if that works like I have outlined, but not guarantees:
I managed to get hold of a Windows 10 pc and I downloaded the Microsoft Digital Rights Update tool.
It didn't remove the DRM protection, a message said:
No .wma files with removable copy protection were found.
It seems some wma DRM protected files have an additional layer of protection in the form of a license.
Microsoft suggest that it might be possible to remove the drm protection if the individual in question still has the original Windows pc that the protected wma files were ripped on to.
the method is to copy the license from the old pc
to Win 10. Tools>manage licenses>Change & then backup license