everytime i try to switch back to the default windows theme, it always says---ERROR: could not find LiteStepDir, exiting

theme was not installed!!!!!!!!!!!!!! can someone tell me how to fix it?

Just a suggestion. Try to 'ctrl,alt,del' then check your applications and tasks menus, do you see litestep.exe? If so it is installed. Maybe you moved some files by accident? If you want to go back to 'Explorer.exe' (windows default shell) then terminate litestep.exe though the tasks menu (ctrl, alt , del) after litestep terminates restart your computer. "ctrl , alt , del " then click on 'shutdown' then 'restart'. When windows restarts remember to hit "F8" to load to 'Safe Mode' When you load to safe mode it will load 'explorer.exe' by default. See If you can now uninstall litestep. Then if you can, after you do, reboot your computer again, and then try to reinstall litestep. Make sure your computer us up to date will all updates and patches first.
Hope this helps. I had problem like this before. For me to solve it I had to let litestep to install into its default directory.

You do not have to get into Safe Mode to uninstall LiteStep...heck you don't even need a shell loaded in XP/2K/NT to do it. After you delete it you don't even need a reboot. However...your answer had nothing to do with the question so we digress.

You say when you try and switch back to the default windows theme you get the error. However...do you mean when you try and switch to explorer you get the error, because that I don't think would be possible, or do you mean you are installing a LiteStep theme that looks like explorer. If you are doing the later of the two it means you didn't boot directly into LiteStep. Once you boot right into LS, instead of starting it from explorer and killing explorer, $LiteStepDir$ will get set for the app looking for it and you should be fine.