Comment 6 for bug 1292396

It's a really critical bug. It has wasted my 6 hours to fix this bug. I had raised a query there on askubuntu.
http://askubuntu.com/questions/552581/unity-dash-as-well-as-terminal-is-not-coming

Reinstalling ubuntu-desktop worked for me. Solution by given by remyseroos (http://askubuntu.com/users/230093/remyseroos)

The current work-around is:

From a terminal:

sudo apt-get update
sudo apt-get install unity
dconf reset -f /org/compiz/
This will reinstall unity and reset the config.

If that doesn't works then:

sudo apt-get update
sudo apt-get install ubuntu-desktop
rm -f /home/user/.config/dconf/user
but be aware that this solution will install all of the packages from ubuntu-desktop (including things like gedit, sound utility, archive managers etc.)

Thanks