It's very unlikely that they'll reopen a closed case, but you could try clicking on "ebay help" at the top of the page then click on "Buying" then go to "get help with an item that hasn't arrived" then scroll down the page to the "contact us" icon.

As soon as you are able ask to speak to a supervisor and ask them.

If that fails and you paid by Paypal you could go to their "resolution centre" and claim through there.