It sounds like clicking Continue enabled Sync Library or changed how your computer’s music library syncs with iCloud. Your playlists may not be permanently lost, but it’s important to avoid making further changes until you check.
- Check another device: Open Music on your iPhone or visit music.apple.com and see whether the original playlists and songs are still there.
- Check the Windows library: In the Apple Music app, select the sidebar actions button -> Library -> Update Cloud Library and allow it to finish syncing.
- Protect your existing library: If you still have the original library on your Windows computer, back up the Apple Music media folder and library files before trying to restore anything.
Apple Music Sync Library isn't a backup service, and turning it off can remove downloaded music from devices. So don't turn Sync Library off or on again just yet.
More info: If songs are missing from your music library.
The most important thing to determine is: Are the missing songs and playlists still visible on your iPhone, or have they disappeared there too? That will help determine whether the original library is still available to recover.