Try the following suggestions below to try to get back your account.
LOST/STOLEN ACCOUNT
Well before you do that again see if you can log into the official yahoo log in site and then also the yahoo email site.
Check Your Name and Password at this Official Yahoo log-in site to check your account>>>
http://help.yahoo.com/l/us/yahoo/edit/ click Sign in at top and it will take you to the official sign-in site.
Check to see if you can log into yahoo mail here >>
http://mail.yahoo.com/
If you cannot sign into either site then most likely you have fallen victim to one of the password stealing scams, read here about them Learn about Password Scams and how to protect yourself from them at >>
http://security.yahoo.com/password_scams… .
If you think your password/account has been stolen then read the following link:
Want to Recover a Password to a Lost or Stolen Account read this >>>
http://www.bigblueball.com/forums/186568… .
Step one on here is just if you forgot your password and would like to get a new one. If you have already tried this and move on to step two and three and four. Please note you will need to know your original account details such as your birth date, Yahoo ID, secret question and answer or your alternate e-mail address.
If you are not able to get your account back there will be no way for you to close it.