Attempt to re-install ubuntu-software fails: "no installation candidate" [duplicate]

For some reason my ubuntu-software-center disappeared (on Ubuntu 18.04).

I tried the usual

sudo apt-get update

and

sudo apt-get install software-center

But I end up with this error:

Package software-center 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 'software-center' has no installation candidate

How can I solve this issue? I tried with synaptic but it did not work out.

I don't think Ubuntu Software Center has that name for its package; when I entered the command apt search, I didn't got that package name in the results:

$ apt-cache search software-center
app-install-data - Ubuntu applications (data files)
software-center-aptdaemon-plugins - The aptdaemon plugins for software-center
ubuntu-kylin-software-center - Software maintenance management tools

The Software Center package is named gnome-software (if you're using the GNOME desktop) on Ubuntu 18.04

$ apt-cache search gnome-software
gnome-software - Software Center for GNOME
gnome-software-common - Software Center for GNOME (common files)
gnome-software-dev - Software Center for GNOME - development files
gnome-software-doc - Software Center for GNOME - documentation
gnome-software-plugin-snap - Snap support for GNOME Software
gnome-packagekit-session - Transitional package (gnome-packagekit-session -> gnome-software)
gnome-software-plugin-flatpak - Flatpak support for GNOME Software
gnome-software-plugin-limba - Limba support for GNOME Software
libflatpak0 - Application deployment framework for desktop apps (library)

So if you want to reinstall it, just type

sudo apt install gnome-software