windows xp shell deleted itself

i have just installed windows xp on my machine which worked fine. after
installing a few updates (i am unclear which one exactly, I can not set up
the computer for windows xp appearance.

on desktop > rt cilck > properties > appearance > under windows and buttons
I have lost the options for xp classic, silver or olive which can normally be
found there. how do i get these options back?

this is not an optimisation setting that i have done for performance, i have
checked that as well as running system restore to try to get the option back
but even taking the computer back until any of the installations of updates,
the xp styles do not reappear.

how do i get them back?

thanks,
ben