Linux Olivia 15 - apt-get - Not found [IP: 91.189.91.14 80]

Hi there, this morning I came across this very annoying message from my linux Mint (Olivia 15):

Err http://archive.ubuntu.com raring-updates/universe i386 Packages 404 Not Found [IP: 91.189.91.14 80] Err http://archive.ubuntu.com raring-updates/multiverse i386 Packages 404 Not Found [IP: 91.189.91.14 80] Fetched 163 kB in 23s (6838 B/s) W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/main/binary-amd64/Packages 404 Not Found [IP: 91.189.92.201 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/restricted/binary-amd64/Packages 404 Not Found [IP: 91.189.92.201 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/universe/binary-amd64/Packages 404 Not Found [IP: 91.189.92.201 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/multiverse/binary-amd64/Packages 404 Not Found [IP: 91.189.92.201 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/main/binary-i386/Packages 404 Not Found [IP: 91.189.92.201 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.92.201 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/universe/binary-i386/Packages 404 Not Found [IP: 91.189.92.201 80] W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/raring-security/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.92.201 80]

So... after a while I've found that this is probably caused from Raring Ringtail (13.04) becoming EOL!

I've opened Synaptic, and then I've disabled old raring* repos.
The problem is that while trying to add new repositories, it suddenly crashed leaving me alone with a worse problem: apt-get stopped working at all.

Then, the solution:

sudo nano /etc/apt/sources.list

mine looked like: 
# deb http://archive.getdeb.net/ubuntu/ raring-getdeb ap ps games 

# deb http://repository.spotify.com/ stable non-fre e 

I've added: 

deb http://archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse 

It works like a charm!

Cheers,

pietro