Unity and Ubuntu-desktop disappeared and I am unable to reinstall it!

Question

I am running Ubuntu 13.04. After running a normal upgrade, Unity disappeared (after login, I have the desktop, without the launch abd status bar, no dash, etc.).

If I try to reinstall ubuntu-desktop, I get unmet dependencies:

vmalep@x220t:/mnt/sda2/home/vmalep$ sudo apt-get install
ubuntu-desktop    Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution  that some required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies.
ubuntu-desktop : Depends: unity but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Unity is a bit more explicit:

vmalep@x220t:/mnt/sda2/home/vmalep$ sudo apt-get install unity
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies.
unity : Depends: libunity-core-6.0-5 (= 7.0.0daily13.04.18~13.04-0ubuntu1) but it is not going to be installed
  Depends: unity-common (= 7.0.0daily13.04.18~13.04-0ubuntu1) but 7.0.0daily13.05.16ubuntu.unity.experimental.certified-0ubuntu1 is to be installed
  Recommends: gnome-control-center-unity but it is not going to be installed
  Recommends: unity-lens-friends but it is not going to be installed
  Recommends: unity-lens-shopping but it is not going to be installed
  Recommends: indicator-bluetooth but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Solution

Try these commands:

sudo apt-get install --reinstall ubuntu-desktop
sudo apt-get build-dep ubuntu-desktop

This should re-install the Ubuntu desktop and build the dependencies.

Hope this helps.

Comments

[desgua]

It is probable that you added some ppa. I think it could be solved with ppa-purge. Do you know which ppa have you installed recently?

[vmalep]

Hi Desgua, You are right, this was linked to the "experimental certified" option I had installed (and maybe not properly removed): omgubuntu.co.uk/2013/05/unity-previews-enhanced-toggles. I reinstalled it and then, removed it with ppa-purge and it is now sovled.

[desgua]

Great! Now you can answer your own question to help others users that came here or I can do that for you ;-)

[Vins]

@desgua and vmalep : Even I'm facing the same problem , how to know the recently installed PPA and remove it ?