The information that can be determined by a barcode is limited. Because barcodes are on items that are distributed about the world at thousands of different retailers, they are identical for all identical products. You cannot tell from a barcode where an item was sold, but you can find out the distributor that owns the barcode for the item you are researching in order to narrow your search for your item's retail or wholesale outlet.
Enter the barcode you are looking for into an EAN search engine such as at Decept Dropship or EANdata to determine who bought the barcode of the item you are researching (see Resources). EAN stands for European article number.
Research the buyer of the barcode by locating their website to find out more information about your particular item.
Call or write to the barcode's owner to see if they have a record of your particular item in their inventory database. They may be able to narrow down the particular outlet at which the item was bought.
If your EAN code does not come back with certain hits, you may have an American item which has a separate system. This is known as UPC, which stands for universal product code. Search for a specific UPC search engine if a regular EAN code search fails (see Resources). Some UPC search engines (there are several available) will tell you where a particular item is for sale still. This can be particularly handy if you are looking for something you bought a while ago or if it is an out-of-print book.