The package g++-9 needs to be reinstalled, but I can’t find an archive for it

Hello everyone! I’m new using Zorin. Meanwhile installing the software update I’ve accidentally shut down the computer. Now, the whole screen is black yet it looks like it’s working on the background. There’s an error with the prompt:

“An error occurred, run the package manager with the right mouse button over the menu or apt-get in a terminal to see what is happening. The error message is: "Unknown error: "class 'apt_pkg.Error'" (E:The package g++-9 needs to be reinstalled, but I can't find an archive for it.)». Normally, this means that you have installed packages whose dependencies could not be satisfied.”

I’ve got no idea what to do. Everything helps!

You can reach the recovery menu by tapping esc or tab (On EFI Boot systems) at boot to reach the Grub menu.
Select Advanced Options for Zorin
Then select Zorin on -kernel- (Recovery)

This will take you to the recovery menu. From here, arrow key down to Enable networking. Once networking is enabled, back up to the recovery menu and arrow key down to Root - Drop to root prompt
Tap the enter key and then run the following commands.
First, ensure that the Ubuntu Multiverse repository is added/enabled:

sudo add-apt-repository multiverse

Update your sources:

sudo apt update

Install the package:

sudo apt install -y g++-9

sudo apt install --reinstall zorin-os-desktop

If the above all installs with no errors, run

sudo apt full-upgrade

If no errors - test booting up normally.
If errors, please relay them here.