This question already has an answer here:
I recently asked a question with an unregistered account here:
This account now has reputation, and my question has generated discussion I'd really like to participate in. Unfortunately, however, my cookies have been deleted since I created that account. Now, there does not appear to be any way to recover or even log into the account. When I clicked the emailed link to register the account with a password, this account was created instead.
Unfortunately, this account does me no good, as I'd really prefer to continue the discussion with my old account.