Problems with Updates & Software, add-apt-repository and "Can't find a source ..."

[Bashing-om]

v3.xx; braneludio; Hey guys;

I am invited to join this thread, see what we can do.

v3.xx has my thoughts and we follow his lead as he is the 1st responder.

upfront, maybe

look'n for that needle in the haystack

[v3.xx]

Here's Bashing-om reply to my PM.

So many DE's installed, and we have a conflict of interest when the OP tried to remove, No telling what will now have to be replaced, just trial and error with ' apt-get upgrade ' .
Make sure all the PPAs are supported in trusty; temporarily disable all of them until the package manager is stable;
results -> apt-get -f install ?
results -> sudo dpkg -C -> ?

Focus on getting the system stable using the default DE ,unity, up and running as the display manager .
Run sudo dpkg-reconfigure lightdm to set the default display manager

Then we see where we stand.