Hmm. I'm sorry to say that I really don't know how you could access the picture again through your own computer; it might be hard, especially if your browser's history has already been deleted (most delete all sites that have not been accessed in a certain number of days).

However, you might be able to access an old copy of the page using Google's search engine. Try running an Advanced Search for the page you want, and choose to include cached pages.

Also, might actually have more luck using an archiving website like the Internet Archive Wayback Machine, which archive sites so that they can be accessed again at a later date - even if the pages have since been changed or deleted.

Anyway, good luck in finding what you want, and in making that dress!