Just saw this:
What is the achievement, and who was the removed user?
Just learning how this website works, thanks
A user downvoted your post, and you lost 2 rep. The user account was later deleted (for reasons we don't know), so any votes they cast on your posts were reversed, hence the refund of 2 rep.
Votes (up/down) are anonymous, so we cannot know who the user was.
Read more on MSE FAQs.