Not sure the legalities of what has to happen with the money since it was a business expense for a company that no longer exists - perhaps a lawyer would be the one to consult with for advise on that.

But if you're all clear on that, can't you just change the ticket to the cheapest one-way you can find - probably a highly competitive, cheap, probably high-frequency route, like SFO-LAX, and then take the balance as a voucher that you can use within a year. Obviously, if there are change fees on the existing ticket, you'd have to pay those first.