Did the bank send the refund back because of a wrong or closed account? That could take several weeks or longer for the check to come in the mail.
If you chose to have a check mailed when you filed your return:
If you refund has been mailed, then it takes the normal amount of time for the U.S. mail system to put it in your mailbox. About 7-10 days average. Watch your mailbox and open all mail even if it looks like junk mail.