You cannot get a new Simple Delivery label.
Best way forward here is to refund the buyer then relist the item if they ,or someone else wishes to buy the item, as they are not replying to your messages.
Cancel the order selecting Problem with Buyer's Address. This fully refunds the buyer, and your seller performance is not affected.
Send the buyer another message explaining what you have done, and their refund will go back to their payment source, which if paid by a card payment, can take 30 days to appear in that account.
@will_6370