if you know the id of the particular seller - go to advanced search (on the right of the big blue search button) at top of page and then on the next page you come to - under items on menu on the right of the page select by seller.
In the next page you come to, input sellers id into square under sellers ID.
If you are not quite sure of exact id - you can also use search by member function to input a sellers name - as you remember it and it will bring up matches and close matches information
