I upgraded my Hp g6 from ubuntu 13.10 to 14.04 yesterday.

Now I cannot log into the system using ubuntu/unity

But I can still login using i3 windows manager.

I checked and found the ubuntu-desktop is broken. I tried to reinstall it, it complained about the dependency issue and broken package.

   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 resolve the situation:

   The following packages have unmet dependencies:
   ubuntu-desktop : Depends: ubuntu-session but it is not going to be installed
      Recommends: empathy but it is not going to be installed
      E: Unable to correct problems, you have held broken packages.

when I tried to install ubuntu-session,

    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 resolve the situation:

    The following packages have unmet dependencies:
    ubuntu-session : Depends: gnome-session-bin (< 3.10) but
    3.10.1-0ubuntu1~saucy1 is to be installed
    Depends: gnome-session-common (= 3.9.90-0ubuntu12) but            
   3.10.1-0ubuntu1~saucy1 is to be installed
   E: Unable to correct problems, you have held broken packages.

I tried

    sudo apt-get install -f

but it does not work

Any help would be highly appreciated. Thanks.