Can you install any packages? For example
Code:
sudo apt-get install --reinstall mono-common
Since usually if apt gets messed up, you can't do anything. If you can do something, it's not deadly
Removing packages (especially ones that have a lot of dependencies) is generally not a good idea in this sort of distributions; it's easy to remove something that is more or less essential for the system to run. And it's not difficult to remove something, that depends on and removes something else, that depends on and removes something else that is then important. It is a pain keeping some packages up to date with this sort of operating systems where you rely on a package manager with dependency checks (that don't make your life easy while trying to upgrade one single package from source), and I wouldn't recommend this way of building something from source and in the process removing a binary package that has dependencies.
It is possible there is an error somewhere (for example in a script that is executed only when a package is removed, so that the error is not found during installation of that package, and since most people don't remove that package at all, the error stays hidden until you bump into it) in some package, and this is about it. Not sure, but running apt installing something, for example, should tell if it's working or not. You may have to run dpkg to configure the packages (that's one thing I mostly bump into: apt process is interrupted, after which the configuration needs to be run manually before anything else works), but if so, apt tells you that.
I would recommend doing it the apt way when upgrading a single package:
1) try to upgrade it from a reposity, if it is there
2) if it's not in the reposity, try to find a reposity where it is, or at least a single Ubuntu .deb package off the web that you can use to upgrade trough dpkg
3) if there just isn't a .deb for you, build one, and use that to upgrade - don't rush into source compilation bypassing the package manager
This is because the distribution was planned to be kept up to date with the package manager. Anything you do bypassing the package manager goes by it, and causes trouble whenever another matter depends on the manually-installed thing. The right way, when doing something "manually", is to package that manual job into a .deb and have apt install/upgrade that deb, thus keeping the strings at apt's hands rather than throw them overboard. Package management was invented to make life easier and keep track of files installed, and installing something from source (bypassing the package manager part) means "cheating" the package manager and since the package manager isn't actually intelligent, it won't fix your mistakes.
So: after you get your apt working, find a guide to build the source code and instead of installing it (as in "make install") turning it into a .deb package, and use that way. It just saves you a lot if you learn it once.
