I have edited my sources.list because I couldn't do update because it throws a series of error code 404. I followed some steps on the internet so it would lead to id.old-releases.ubuntu.com, but it's still failed (I was trying to download samba for my school's project and I got panicked because of it). I haven't backup my sources.list file, and I'm confused what to do now.
This is what the code that I use to change the
$ sudo sed -i.bak -r 's/(archive|security).ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list
Most of the errors that I got were similar like this.
Err http://id.old-releases.ubuntu.com vivid-backports Release.gpg Could not resolve 'id.old-releases.ubuntu.com'
Could anybody help? I don't really understand how Ubuntu works.