Removed resolvconf can't install anymore

Question

As stated in the title, I removed resolvconf (with reinstalling in mind because name resolution was acting up) but now I'm unable to install this package.
I tried two things:
apt-get install --reinstall resolvconf
resulting in the following error:

Package resolvconf is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source

E: Package 'resolvconf' has no installation candidate

Using apt-get install resolvconf I get the same error.

Answer 1

Test this:

Open a terminal,

Press Ctrl+Alt+T

Run it:

sudo -i
wget http://fr.archive.ubuntu.com/ubuntu/pool/main/r/resolvconf/resolvconf_1.69ubuntu1_all.deb
dpkg -i resolvconf_1.69ubuntu1_all.deb

Answer 2

Grab the download URL domain:

$ sudo apt install resolvconf
...
E: Impossible de récupérer http://fr.archive.ubuntu.com/ubuntu/pool/main/r/resolvconf/resolvconf_1.78ubuntu2_all.deb

Resolve it manually using OpenDNS server (provided you have nslookup, otherwise use some online DNS resolver):

$ nslookup fr.archive.ubuntu.com 208.67.220.220
...
Non-authoritative answer:
Address: 194.158.119.190

Edit your hosts file:

$ gksudo gedit /etc/hosts &>/dev/null &

Add:

194.158.119.190 fr.archive.ubuntu.com

Retry to reinstall resolvconf:

$ sudo apt install resolvconf

Disconnect / reconnect your network from network-manager.

Test.

Remove the now useless entry from your hosts file.

Answer 3

I manually downloaded this package: http://fr.archive.ubuntu.com/ubuntu/pool/main/r/resolvconf/resolvconf_1.78ubuntu2_all.deb

Instead of this one (which was giving me a dependency error when dpkg it for Ubuntu 18.04): http://fr.archive.ubuntu.com/ubuntu/pool/main/r/resolvconf/resolvconf_1.69ubuntu1_all.deb

My configuration is Ubuntu 18.04.