I've been spending many hours after installing a clean 1.9.3.3 magento with all the security patches for a new website, my admin top nav bar menu was not displaying. I searched the web and didn't find any solutions. I just wish to share this solution that I found and that works.
If you install or update to 1.9.3.3 and have same problem, try this:
Go to yourwebsite/magento/downloader/ or yourwebsite/downloader/ ( Magento Connect )
Re-install these packages:
Mage_Core_Adminhtml
Interface_Adminhtml_Default
Mage_All_Latest
Mage_Core_Modules
I dont know which one did it, but I reinstalled all of them and it worked!