User Account - help me

Hello guys, I have Sony Vaio VGN-FW550F since one year. I have never set -up any User Account and password.
Today I wanted to do it and I created new User Account called ELI. Unfortunatelly, as soon as I restarted my PC, he offered me two options/ accounts: to access either with the new account ELI or to access with the old account called SONY for which I am supposed to insert the password (which I don't know, I HAVE NEVER SET IT UP). Is there any default password for Sony user account??? I have all my files and photos over there.... I am really desperate. I have never ever set up any administrator or user passwords....
Please, help me . Thank you in advance, Elizabeta

Hi guys, thank you very much for trying to help me. The problem is that WHATEVER I touch (Restore point options, create system repair disk and similar), it appears User Account Controll and it asks me the Sony account password... Is it possible or I am doing something wrong...? I am logged on in the new account ELI and I am working from that account. Is it possible that my old User Account called Sony asks me the password? I have NEVER EVER seted up anything....

Hi, I do have some other PC at home (can be any PC?) but I don't have any Windows installer disk at home. When I bought my Vaio PC, Windows 7 was already installed... The only thing I did is that I created some Recovery disks that "registered" the initial situation on my PC (before I installed my programs, download my photos and so on). Can it be helpful?

Hello to everybody and THANK TO EVERYONE THAT TRIED TO HELP ME!!! I resolved the problem and now I will tell you what happened, muybe it will help to somebody else with my same problem. This morning I tried to install parental security controll and I downloaded the program called K9 Web protection. During the download/ installing, the program asked me to insert the Administrator password so I put one new password for this action, in order to activate the parental controll. I was never re-routed to my user account, guest account, administrator account or whatever. I remained "inside" this Web protection program while putting the password so I have NEVER IMMAGINED that this will automatically change my basic computer settings. When I finished the downoad I was no longer able to enter in my Account (IT IS VERY LOGIC, I KNOW...) because my Sony user account "picked up" the password I have inserted.
I am not an expert but for me it would me much more logical that, while downloading the program, it appears the message that you FIRST have to add a password to your User account and then you can proceed with the download... Thank you very much, I learned many things today :).