HGG Community Forums

If you go to "Account and Stable Management" on the Member Home page, there's a link that says "Associated Accounts List" - click that, and it will list any accounts registered with your email up at the top, as well as any other accounts that have become "associated" (which, from my understanding, is based on IP address, so may be total strangers :) )
That ought to at least let you see what your other username(s) might be, and you should be able to view barns for those as well from there. Might have to do a password change, but if you have a username and the email, that's not bad.