Fantasy is my #1; I will give almost anything a chance if it has strong fantasy elements. Post apocalyptic, superhero, alternate history, science fantasy, some supernatural, romance, and a few fandoms (especially Game of Thrones) are also likely to catch my eye.
I don't think there's anything you can do to restore it yourself. However, you can probably be invited back into the conversation by anyone else who was part of it and you'll be able to see it all again.
If you haven't permanently left it, a reply to that PM ( from the other participants) will pull it back up for you. If you permanently left (Ignore future messages), then... No way, lost forever.