My bounty that I made several days ago has disappeared, and my reputation has been given back to me. I didn't close the question or the bounty. My Reputation tab used to have -100 on it and it disappeared too.
It wasn't an action by a site moderator. Your question got automatically removed because it met our criteria for automatic deletion: it was posted over a year ago, had zero votes, and after you deleted your answer on September 6, no answers.
I can undelete the question and your answer (to prevent the question from getting auto-removed again) and you can offer the bounty again if you want to try and have another go at it. Let me know in a comment here.