For purchases from the Ticketmaster website with a card, the money is automatically refunded to the credit or debit card from which the purchase was made. Your account update depends on the procedures followed by the issuing bank of your card.
For purchases from ticket offices or the Public stores, you will need to go to the store from which the purchase was made in order to get your money back. If the purchase was made by card, you will need to have it with you when visiting the store.