Without seeing what you're seeing, it's hard.
You should be able to get to the Control Panel from the Windows Start button, but I don't know if you're saying you can't get back to that or not and not all Start menus are set up the same, so yours may not say Control Panel.
If you can't access the Start menu, did you try switching users and then selecting yourself from the user list? That will often let me back in.
Have you rebooted? Always reboot, because sometimes that fixes things and you may be able to get back to the control panel after a reboot. If you can't get to the start button within Windows, use the button on the machine.