Q: can see anything in my library

From what I understand, you lost the songs from Apple Music in your library.

Are you subscribed to Apple Music right now? Is it possible you unsusbribed, waited a certain amount of time, then subscribed again?

Have you made sure your Internet connection was working properly?

Have you made sure you were using the same Apple ID as before?

Is iCloud Music Library turned on? (Use your Apple Music membership to get your music on all of your devices - Apple Support)

Are you using more than one device to access your music library? Which kind of devices are you using (iPod, iPhone, iPad, Mac, Windows PC, Android device)?