Without postal tracking you can't show delivered but if you open the original postage label that will mark it as dispatched.
It will still be unused and if the buyer pays postage the cost will be automatically refunded to them in 30 days.
As the item is untracked ebay will hold the payment for 14 days and then you will receive it.
I've just checked and see you also had collection in person on your listing. If the buyer selected that you need to ask them for the collection code they will have received from ebay when they paid. On a desktop you can manually enter the 6 digit number in View Order details.
