I screwed up my Steam installation, how do I fix my broken packages? - ubuntu-18.04

Question

I have Ubuntu 18.04, not installed directly but upgraded from 16.10, I haven't used Steam in a while on this computer (maybe since before the 18.04 upgrade, don't remember) which led to problems, and after a while of trawling the Internet for possible solutions, I had to admit defeat.
I tried the sudo apt-get autoremove/update/upgrade/dist-upgrade series, and it didn't do anything.
EDIT: I have also done sudo apt-get clean, and sudo apt-get install -f.
I also tried a full uninstall via deleting .steam/ and .local/share/Steam/ .
I am aware of the method of simply manually installing the packages, but that isn't working for me, either. Observe:
$ sudo apt install steam
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:
steam:i386 : Depends: libgl1-mesa-dri:i386 (>= 17.3) but it is not going to be installed or
libtxc-dxtn0:i386
Depends: libgl1-mesa-dri:i386 but it is not going to be installed
Depends: libgl1-mesa-glx:i386 but it is not going to be installed
Recommends: nvidia-driver-libs-i386:i386 but it is not installable
E: Unable to correct problems, you have held broken packages.
From this, I tried to run the following commands:
$ sudo apt install libgl1-mesa-dri:i386
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:
libgl1-mesa-dri:i386 : Depends: libllvm8:i386 (>= 1:8~svn298832-1~) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
$ sudo apt install libgl1-mesa-dri:i386 libllvm8:i386
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:
libllvm8:i386 : Depends: libatomic1:i386 (>= 4.8) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
$ sudo apt install libgl1-mesa-dri:i386 libllvm8:i386 libatomic1:i386
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:
debhelper : Depends: dh-autoreconf (>= 17~) but it is not going to be installed
libatomic1:i386 : Depends: gcc-8-base:i386 (= 8.3.0-6ubuntu1~18.04.1) but 8.3.0-16ubuntu3~16.04 is to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
At this point, I don't really know what to do. Especially in response to the line "but 8.3.0-16ubuntu3~16.04 is to be installed". I have Ubuntu 18.04. Why is something from 16.04 going to be installed?
One more try for completion's sake:
$ sudo apt install libgl1-mesa-dri:i386 libllvm8:i386 libatomic1:i386 dh-autoreconf gcc-8-base:i386
Reading package lists... Done
Building dependency tree
Reading state information... Done
gcc-8-base:i386 is already the newest version (8.3.0-16ubuntu3~16.04).
gcc-8-base:i386 set to manually installed.
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:
dh-autoreconf : Depends: libtool (>= 2.4.2) but it is not going to be installed
libatomic1:i386 : Depends: gcc-8-base:i386 (= 8.3.0-6ubuntu1~18.04.1) but 8.3.0-16ubuntu3~16.04 is to be installed
E: Unable to correct problems, you have held broken packages.
And including gcc-8-base:i386 does nothing.
How did I break my install of Ubuntu?

Answer 1

Tried all top Google solutions. None of them worked for me.
Came across this answer that described how we can reset broken packages.
Take a backup of the file /var/lib/dpkg/status first. Then erase all the contents of that file.
Then run sudo apt install steam. It may prompt you if there are files that already exist and will be overwritten. Best that you check for the differences in the file's contents. In my case, I decided to use the one from the package maintainers itself instead of my own.
Steam installed smoothly. Did not get any unmet dependencies error.
When I tried to start steam, I got an error about glxchoosevisual failed. For this, I then had to install libnvidia-gl-450:i386 library. Note that in my case, my nvidia driver version was 450 so used that. You need to use your version here. That's it! Steam then launched fine.
Sharing it here in case it helps somebody.

Answer 2

Check if you have enabled restricted and universe repositories.
You can also run:
This cleans the local repo from packages so they are going to be downloaded again
apt-get clean
This is reinstalling broken packages
apt-get -f install