At a minimum, you can get a refund/credit
if the charge for your tickets appears on a credit card statement mailed to you within the past 60 days. Otherwise, legally, you might well be out of luck, unless your credit card company has a specific provision designed to protect you. However, most credit card companies have a more generous (unpublished) refund policy than the law and federal regulations require, typically covering charges as old as six months or so.
See this
Federal Trade Commission link for the rules as to what to do. Note that unless you send a
written dispute letter via
certified mail, your claim might well be denied.