Hello Carondoian,
Thank you for using Apple Support Communities! I understand that Apple Music content has disappeared unexpectedly from the Music app on your iPhone, however you are still able to see your music purchased from the iTunes Store. It's important you're able to listen to your music when you want, and you've come to the right place for help.
Let's start by making sure you're signed in to Settings > iTunes & App Store with the same Apple ID you use for your Apple Music subscription. After that, confirm that iCloud Music Library is enabled:
Turn on iCloud Music Library with Apple Music - Apple Support
When you use iCloud Music Library, it syncs your music across devices using iCloud. Similar to other iCloud services, signing out of your Apple ID or turning off iCloud Music Library will remove the synced content from your device. You will need to download the content for offline listening again once your playlists reappear:
Add and download music and video content from the Apple Music catalog - Apple Support
It may also be a good idea to check if you have any storage restrictions for downloaded music from Settings > Music > Optimize Storage. Turning on Optimize Storage will automatically remove downloaded music to save space on your device.
Let us know if there's any change after trying these steps.
Take care!
