very strange problem/challenge: Missing much of dashboard!!

[Title & text de-capitalized, please do not shout at us]

Okay, here’s a challenge for everyone: over half the admin menu items (plus main sections in the dashboard) are missing!
see a screen shot here: https://www.fcucc.org/wp-content/uploads/wordpressproblem.pdf
When I log in to my dashboard, most of the menu items on the left side column are missing: Posts, Pages, Links, Comments, Appearance, Plugins, Tools… Some items still there: Users, Settings, and the Media library. When I click on any of the menu items, I get a ‘You don’t have sufficient permissions to access this page.’ error. The online site appears fine, although is a little wonky because plug-ins are currently disabled: https://www.fcucc.org

I’ve done the most obvious trouble shooting:
1.) reinstalling 3.5 (both auto and manual)
2.) disabled all plug-ins via FTP
3.) updated theme
4.) checked theme change-log; fully compatible with 3.5
5.) replaced wp-admin and wp-includes folders from a fresh download of 3.5 via FTP
6.) added a new user with admin level access to see if it was a role/access issue
7.) switching to default theme (by renaming theme folder via FTP)…menu items still missing in default theme
I’ve googled and searched the support forums here for hours. And contacted the theme developer.

Possibly due to:
? All-in One Events Calendar plug-in?…had lots of issue with that plug-in, but it’s currently disabled and deleted from plug-ins folder
? permissions or roles?

thanks for any help!! I have been troubleshooting this off and on for two weeks!!! I’m about to ask my host for a back-dated back-up….but surely there is a solution among the wordpress pros out there! ??