If you had used Ubuntu 13.10 and fiddled around with the menu settings you may have found that when you upgrade to 14.04 some of the menus appear odd. Two things I noticed:
- In Nautilus I found that the silly icons that replaced file menus were still there after the update but were not there in a fresh install of 14.04.
- In firefox the menus were absent no matter what menu position that you selected in All Settings -> Appearance in the System Settings.
I traced the problem (after a lot of going around in circles) to the fact that I had tweaked things in Ubuntu 13.10 and this had unintended consequences during the upgrade.
So in 13.10 I had used this web-page: www.webupd8.org (or similar) to remove the
appmenu-gtk appmenu-gtk3 appmenu-qt indicator-appmenu packages.
When you search in 14.04 they have been replaced with other packages – I searched and installed these manually and solved all my problems!
A quicker solution would be re-install
indicator-appmenu and this should pull in all the dependencies that you need:
sudo apt-get install indicator-appmenu