Why All My Messages And Folders Have Been Erased By Yahoo Services ?

I reported three times an abuse from yahoo account services. I received only standard inappropriate answers which didn't solve my problem. I have been a yahoo user since 1998. I never had any complaint or problem, excepting the virus that sent emails to all my contacts from the address book but this is another story. On the 2nd of January 2012 I have received an email from yahoo account services in which I number, alternative email, secure question, user name and password. The message was threading me that it was mandatory to provide this information otherwise my yahoo account was going to be erased. I answered back to this email in which I have provided all the requested information.  I have been a longtime yahoo user (over 14 years), and I had many folders and important messages kept in Inbox and Sentbox.  On the 4th of January, when I accessed my account (with no difficulty), I found out a completely new account, without any message or folder in it. All my old/saved folders have disappeared /gone. It was a completely empty account.  I hadn't and I don’t have any problem with recovering my password or accessing the account.  I repeat, the problem is that I have now a new account like any new comer who became a yahoo user a few days ago.  What I was asking to yahoo custom care was to restore my old folders and emails.  I want my old account BACK, as I haven’t been warned about the imminence of the erasing, which I consider a very severe abuse and a violation of my correspondence.