If you are looking for a specific or a rare bonus track that seems to have vanished, let me know! I can help you:
Avoid "free MP3" conversion sites. These platforms are notorious for:
Go to your "Purchased" tab. If a song is missing, check your "Hidden Purchases" in account settings.
Identify which that track originally appeared on.
your account history on the platform where you first bought the music.
Which album are you trying to restore?