My 5th generation iPod don't recognize music as "music"!

Hello,

Recently, I found my old iPod 5th generation in my stuff.

I wanted to add my music from my iTunes Library, unfortunately, iTunes for Windows did not recognize him.

So I found that when I go into Disk Mode, I can add to my music!

The problem: This is when I return to the main menu, there's no song on the list. However, they are well on the iPod because they take space (memory).

What can I do?

Translated with Google Translation from the French.