Incompatibility of iTunes's files

On my WD LIVE TV I can not play MP3 files and M4A recently downloaded itunes, it worked very well before but not anymore since the 10.5.2 version of itunes apparently. 

The version if iTunes on your PC doesn’t matter. Are the files you bought DRM protected?

I do not know, how do I know please. Knowing that these files are MP3 free podcasts.

You’d have to use Mediainfo.

But most podcasts aren’t DRM’d, as far as I know…

You also metioned m4a which according to Wikipedia

Apple Inc. started using and popularizing the .m4a filename extension, which is used for MP4 containers with audio data in the Advanced Audio Coding (AAC) or its own Apple Lossless (ALE, ALAC) formats.

Maybe it’s AAC the live can’t handle in all its variations? Just post output from Mediainfo.