Update and upgrade packages

sudo apt-get update
sudo apt-get upgrade

Add extra repositories

sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup
sudo gedit /etc/apt/sources.list


Add :

deb http://us.archive.ubuntu.com/ubuntu/ gutsy main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy main restricted universe multiverse

deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted universe multiverse

deb http://us.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse

deb http://archive.canonical.com/ubuntu gutsy partner
deb-src http://archive.canonical.com/ubuntu gutsy partner

deb http://security.ubuntu.com/ubuntu gutsy-security main restricted universe multiverse
deb-src http://security.ubuntu.com/ubuntu gutsy-security main restricted universe multiverse

-----save then back to terminal-----


sudo apt-get update