Quoting from "How does the bounty system work?"
Do I get the reputation back when question I placed bounty that was already awarded is being deleted?
Yes. The change is not immediate like other reputation changes but the reputation points are given back. Source - marked status-bydesign is official enough. If the question is undeleted, the reputation is reduced again.
And quoting from "How does deleting work? What can cause a post to be deleted, and what does that actually mean?"
When can't I delete my own post?
You can't delete answers that have been accepted.
You can't delete any question that:
- has an upvoted answer, or
- has multiple answers (even if there are no upvotes), or
- has been closed less than 48 hours ago (to allow for possible reopening)
You can't delete any of your questions or answers if you haven't registered your account (i.e. associated an OpenID with it).
Can a question with bounty be deleted and the bounty back to user on following cases?
- User answer his own question, no upvote, no other answer
- No answer at all
NOTE: I have read When a question that had bounties is deleted, are they automatically refunded? and If a bounty question is deleted after awarding it, what happens?, but seems they discussed questions with bounty awarded. My question is the bounty is not awarded.