I started a bounty to my question ar_sendmail command not working with ruby 1.9.2 and its time is over now. I have received some answers but they are not what I was looking for.
Is there a way to get bounty offer back?
Once bounty is offered/placed it can not be taken back. see How does the bounty system work? for more help on bounty system.
When bounty time period is over and owner has not assigned bounty to anyone yet then half amount of bounty will be awarded to the answer that is given after bounty is placed and has highest votes[minimum 2] among all. In your case no answer fulfill this condition so bounty amount will not awarded to any one. That means you will not get it back.
You may be interested in knowing why?
If system starts giving bounty back then some[not all] users will start playing with system by placing bounty on question and then when they get answer instead of awarding bounty he will take his bounty amount back. So it will become unfair to the person who have wasted time in answering him.