How do I request a refund for an item that I never received and was "lost in delivery"?

I bought an item off the shop around mid August and it was supposed to arrive between September 9 and September 12. Since after I bought it, the item has become unavailable, and the delivery status switched to "lost in delivery." The page also says if I haven't received it I can request a refund. I tried hitting the return button, and it gave me the "Have you received the item?" question. I hit "No," and then it tells me I can request a return or refund once my package delivers. So can I or can I not get a refund for this item. And if I can, how?