Comment 2 for bug 1372798

Hi!
you have a broken system, please run in a terminal :
sudo apt-get update
sudo apt-get install -f

try to upgrade from here:

in a terminal:
sudo do-release-upgrade

if it doesn't work, you have a lot of kernel installed but not the last one for 12.04.5, it will be a good thing to upgrade your system before to be sure your system is OK.

in a terminal:
sudo apt-get install linux-lts-trusty

try to upgrade from here:

in a terminal:
sudo do-release-upgrade

if it doesn't work, then you may have some PPA installed, that may be a source of problems, maybe you will have to remove them, this may be problematic and complicated cause it will be like a puzzle to get back to a normal and stable state.

at this point, it may be a good idea to have a technician with you or you will have to learn a lot of how to purge a lot of packages (don't ever remove network-manager and other basic packages). It may be a lot complicated at this point, may be better to reinstall the system from scratch, but don't forget to make a backup of all your system before.

hope it may help you.