Reinstall litestep, then Uninstall it properly. windows cannot load the shell, since you deleted it. you cannot just delete the folder. if you must, you should first use the "set explorer as shell" icon on your desktop to disassociate it with the shell.

or, if you feel up to editing the registry (though i highly recommend the above method), you can see this thread on changing the shell, though it might be difficult since the thread is how to set litestep as shell, not the other way around :).