no user icon on welcome screen

[palma]

Windows XP Home - Portable
At the Welcome Screen where normally I am asked to click on a user icon to log on ,there are nomore user icons shown.
Ctrl-Alt-Del has no effect.
So I cannot enter Windows , and 'specialists' told me that I had to reinstall Windows and loose datas (I have a backup,but not complete) and installed programs (really losts and it is a big problem)
I have tried to start in safe mode , but I get the same empty Welcome screen

Any suggestion is welcome , but do not forget that I am unable to issue any Windows command ?

Thanks

[Ant]

Start your machine and press F8 to bring up a menu. Choose "Last Known Good Configuration" and see if your computer will start normally.

Or you could try to repair XP rather than reinstall by using the recovery console, which is available on your original CDRom. (You'll need to change the boot sequence to boot from CD.)