Applications don't appear in the Dash (14.04)

As it is only constrained to your user account, it must have something to do with your user.

Maybe one of the .desktop files in your home folder is tripping the launcher up? Can you try moving the files in these folders all somewhere else:

• /home/<youruser>/.gnome/apps/
• /home/<youruser>/.local/usr/share/applications/

e.g.

$ mkdir backup_local
$ mkdir backup_gnome
$ mv .local/share/applications/*.desktop backup_local/
$ mv .gnome/apps/*.desktop backup_gnome/

Then logout, login and see if it changed anything? You can always move them back in if it didn't help. If it did help, try moving them in one by one to which file was the culprit.

EDIT: You can find out which one was malformed:

1. Install the desktop-file-utils package:

   sudo apt-get install desktop-file-utils 
   

2. Check each of the .desktop files for validity using desktop-file-validate:

   desktop-file-validate .local/share/applications/*.desktop
   desktop-file-validate .gnome/apps/*.desktop
   

   Or of course at the different location if you already moved it. It will print nothing if all files are OK. If any of the files are malformed, it will print one error message per line.

   You might also want to check the other desktop files for good measure:

   desktop-file-validate /usr/share/applications/*.desktop
   

At somepoint during my session in Ubuntu 14.04 LTS the application search stopped responding, showing the same error. The solution that I've found is to open the terminal (CtrlAltT) and kill the home scope

$ kill $(pgrep -f unity-scope-home/unity-scope-home) 

The scope has restarted and the application search has resumed its capabilities

actually, loggin out to guest session and reloggin back in as main user just fixed the issue, as I still dont really understand why... but before doing that i spent time trying the above command lines, that had no positive effect in my case. for sure a way to reset clean way these .desktop files, which clearly seemed to be the problem, would be appreciated, or even a way to uncorrupt them in case they are. thx anyway

Did you delete your Zeitgeist database and reboot? I.e.:

rm -rf ~/.local/share/zeitgeist

It seems the most logical thing to do. At the next login, allow up to a couple of minutes for the applications to show up again.

Please note that this is not the same as reinstalling Zeitgeist, which in this case is useless, IMHO.