What happened to my iTunes Music Library?

Serious question. It’s been years since i’ve logged in to itunes - Apple Music now. At one point I subscribed to “Match” or whatever the name was for Apple’s product that converted my mp3 music library to higher quality. I logged into Music to give it a try and noticed my massive collection of music is gone? I’ve been on Spotify for some time, and just wanted to try Music, and was totally surprised to find my previous library is gone.