Hi @hitkiakia
Generally, you do not need the ticket back from the buyer to obtain the refund. These days refunds tend to be automatic. If an event is cancelled the original point of purchase (Ticketmaster, venue etc) will refund to the original purchaser. If you subsequently sold tickets your buyer would get their refund from the site they bought on such as stubhub etc.
If you find that you absolutely require the tickets to be returned to you in order to obtain a refund, you can send a private message to the moderators here @TeamStubHub They can help you out.