That's a better description, actually a great description.
At first, I thought maybe just your desktop wallpaper had changed.
You may be able to get things back to normal with the system restore feature of XP.
Startup computer, click Start>Help and Support>Undo changes to your computer with System Restore>Restore my computer to an earlier time.
There's a calendar that will appear. Choose a date in bold that the computer was working and click that date, click Ok and let it restore back.