Email Outlook 2003 Problems

Hello,

I was wondering if anyone could help me. I have just switched on my PC and ended up at the desktop. The only this is:

1). The desktop image has changed an older image.

2) More worringly, when I clicked on outlook I had to set up the account from scratch. Also, all of my emails have disapeared. The PC was working fine on Friday but today all of my email account details and emails have gone.

I have scanned the pc for a virus but none have been detected. I also found the place where the .pst file is stored but this has been reduced in size from over 1gb to about 7mb.

Any helpful hints on why this happened and how I can locate the emails would be appreciated.

Many thanks,

Richard