Recover Hacked Yahoo Accounts

Solution 1

 In case of a hacked account send a mail describing your problem to account-security-help @cc.yahoo-inc.com Note: please delete the blank space between help and @ which I had to insert because Yahoo can't handle long addresses. 

 Solution 2 

If this doesn't help, call Yahoo: 1-408-349-1572, explain to a customer service person what happened. They will ask you to do certain things and then they compare your original info with the changed info. Within 24 hrs you should get your account back! Many users got their hacked account back with in 30 minutes.