How to fix apt not working in Linux Mint 19 Tara?

Question

linux

I ran into the problem of a non-working application center, an update center, and also apt
that does not work at all In /etc/apt/sources.lists.d/official-package-repositories.list , you need to update the list of repositories. On board Linux Mint 19 Tara. Where can I find them in format?

deb-src http://archive...

They didn’t ban them in Google Yandex, it’s just that iq doesn’t allow you to achieve an understanding of what and with what they eat, probably.
UPD. It's not about the repositories. It's just that apt refuses to accept them, because it says that they are not signed.

Answer 1

The answer came in a simple but radical way.
apt complained about not trusting the repository because "they are not signed" , although on other machines with a similar linux everything works civilly.
It was decided to force trust the repositories. [trusted=yes] has been added before each link in the list of repositories at /etc/apt/sources.list.d/official-package-repositories.list , like this:
+ bionic has been changed to raring in the same
UPD. All bullshit. Hastened. It helped to remove the sources.list.d folder using the command:

rm /etc/apt/sources.list.d/*