How do I fix gnome shell themes?

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http://askubuntu.com – This is my fifth full format and install of Ubuntu in under a month. I finally have my Gnome 3 desktop working again, but again, the Gnome shell themes is not select-able. I have asked the question of how to fix this common issue before, but I have seen no positive resolution. Does anybody know of a simple fix? This is a common issue and I have seen hundreds of postings related to it, but other users only seem to get half-way answers also and it goes unresolved. Would it be advisable to completely purge Gnome desktop and reinstall? If so how would I do this? I cannot use any extensions i (HowTos)