then i used digitalocenas mirrors to update packages.
sudo vi /etc/apt/source.list
type insert or i
add the following lines to list
deb http://mirrors.digitalocean.com/ubuntu-old quantal main
deb http://mirrors.digitalocean.com/ubuntu-old quantal-updates main
deb http://mirrors.digitalocean.com/ubuntu-old quantal-security universe
deb http://mirrors.digitalocean.com/ubuntu-old quantal universe
deb http://mirrors.digitalocean.com/ubuntu-old quantal-updates universe
:x
you may delete the old ones as you wish.
sudo apt-get update
it worked for me. I hope you solve the problem same way.
Thanks!
