It's never a good idea to leave it so long but try looking through your Paypal transactions. You should be able to find the seller's ID from there, and send them a message.
You will still have to ask them for their address which will be tricky now, as the item has gone, and ebay will assume you are trying to do an off ebay deal with the seller.
You could end up with an account suspension, as could the seller.
