Check to make sure you are signed in to the same eBay account you used to make the original purchase.
If you purchased as a guest, see here:
https://www.ebay.com/help/buying/returns-refunds/returning-item/returning-items-bought-guest?id=4065
If you cannot find the purchase in any of your accounts, contact eBay through the Help & Contact page.
Use the "Contact us" link and follow the prompts for your issue and you should eventually wind up on a page with a chat option. Choose that, and the last option that appears in the chat window -- use the "See more" option -- should be "Contact an Agent" to request a call-back if you are in North America.
https://community.ebay.com/t5/Selling/How-do-I-contact-Customer-Support/m-p/32016431#M1783851
Or you can contact eBay via social media:
https://twitter.com/askebay
https://www.facebook.com/eBay/
