Ethical dilemma: What do you do when a vanished independent artist scrubs their entire catalog, but you have the only remaining copies?

Years ago, I really liked this small independent artist, but they recently deleted all of their songs from YouTube and Spotify. They completely vanished from the internet, and because they were so small, no other reuploads exist anywhere(ive looked everywhere for it).

I somehow managed to have the mp3 file of the song. I’d love to contact them to ask for permission, but they are literally untraceable. I'm thinking of posting them so they aren't lost forever, but with a clear disclaimer and massage for the artist so heknows that he can just telle to delete all of it and i will immediately do so. Or should I just let it disappear? What's the best move here?