Did it happen after installing PS CC 2014?
Which operating system do you have?
Make sure you have have the latest version of Extension Manager installed.
Follow the suggestions mentioned under Post #12 Re: Extensions greyed out and check.
Let me know how it goes.
Sorry I forgot to mention that I'm using OSX 10.9.2
Did it happen after installing PS CC 2014? Nope, I've installed 2014 after it's release and both CC were happily living together. Both Extension Manager (126.96.36.199) and PS (14.2.1) are up to date judging by CC app.
I've tried to do as post suggest but nothing changed unfortunately: I've quited everything, renamed the Extension Manager folder both in user and system library, uninstalled, reinstalled, restarted — nothing
I also tried to reset settings, that didn't help either
I also tried to change/repair permissions and did different combinations of deleting/reinstalling EM, but still nothing!
I've tried everything I know, still no result. The menu is greyed out. I can't work without extensions! Do I need to reinstall whole OS so Photoshop could start working as it was, Adobe?