Shortcut, Icons, Files, don’t work.

I made a change to the permissions in the HKEY_CLASSES_ROOT. I found out I changed the wrong item and when I tried to change it back it didn’t work. My system boots and I can view the desktop, however I cannot open programs, files, utilities cannot run, etc. Therefore, I cannot run system restore utility or regedit. I tried a repair install and this didn’t work.
Does anybody have any other recommendations?