Get to Yahoo support and report it and just "stop" the acct. Do another one if possible. You can't hack back in, you'll be as bad as the perputator.

FYI - Posting in this an email address isn't going to help any further as that can be gleamed as welled. You have to keep your email addresses as guarded as possible, posting it in "public forums" helps the undesirables. -----Willy