within 24 hrs Delta allows you to refund any booking back to your original payment methods. beyond that you can not get a refund (to your original payment method) but there is no fee to change to a future flight. However you will need to pay(or get voucher) for the difference between the new flight and the original. The other option is to get a voucher or credit for your original booking. Keep in mind vouchers are usually valid for a year and sometimes can only be used for booking by the original ticket holder. That is my understanding.
请懂的TX帮忙解释一下，谢谢！
within 24 hrs Delta allows you to refund any booking back to your original payment methods. beyond that you can not get a refund (to your original payment method) but there is no fee to change to a future flight. However you will need to pay(or get voucher) for the difference between the new flight and the original. The other option is to get a voucher or credit for your original booking. Keep in mind vouchers are usually valid for a year and sometimes can only be used for booking by the original ticket holder. That is my understanding.