What does ‘disappeared’ mean in this context? Is your music local or streamed or both? If local, is your music still in folders? If streamed, is the service up and still in Settings==>Services? Is the music still in your library and you’re missing all your curations or is the music also missing?
Disappeared can mean a lot of things. As specific as you can be will help.
Please accept my apologies that your return to the forum after a year has been marred by an undeserved and prolonged wait time for a staff response. The team truly appreciates your patience, and we’ve prioritized this thread to make sure you receive a more prompt response time moving forward.
Diagnostics from your account show you have streaming content in your library, but only a small amount (one album) of local content. If I’m interpreting your post correctly, then you’ve lost access to some or all of your library content, including local and possibly streaming content.
Can you please confirm the following?
Are you using an external storage location, like an external hard drive or a network share device?
Are you signed into the same profile in Roon?
What are your Watched Folder settings in Roon → Storage? Please share a screenshot.