If you know a seller’s user ID, you can search for items currently being sold by that seller. If you want to display the seller’s past sales or listings, you can search for completed listings instead.
To search for items by seller:Click the Advanced Search
link located at the top of most eBay pages.
On the left side of the page, click the Items by seller link.
Enter the seller’s user ID. If you’re not sure of the seller's user ID, select the Show close and exact user ID matches option.
Tip: If you don't know the seller's user ID, try finding one item being sold by the seller. To display the seller's other items, click the View seller's other items link in the Seller info section on the right side of the listing.