devi editare con un editor di testo il sources.list esempio
sudo gedit /etc/apt/sources.list
poi copia - incolla queste righe e dai l'update
poi trova tutto
deb http://it.archive.ubuntu.com/ubuntu/ gutsy multiverse
deb-src http://it.archive.ubuntu.com/ubuntu/ gutsy multiverse
deb http://it.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse
deb-src http://it.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse
eb http://it.archive.ubuntu.com/ubuntu/ gutsy main restricted
deb-src http://it.archive.ubuntu.com/ubuntu/ gutsy main restricted
deb http://it.archive.ubuntu.com/ubuntu/ gutsy universe
deb-src http://it.archive.ubuntu.com/ubuntu/ gutsy universe
deb http://it.archive.ubuntu.com/ubuntu/ gutsy-updates universe
deb-src http://it.archive.ubuntu.com/ubuntu/ gutsy-updates universe
deb http://it.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse
deb-src http://it.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse
deb http://it.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted
deb-src http://it.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted
deb http://security.ubuntu.com/ubuntu gutsy-security main restricted
deb-src http://security.ubuntu.com/ubuntu gutsy-security main restricted
deb http://security.ubuntu.com/ubuntu gutsy-security universe
deb-src http://security.ubuntu.com/ubuntu gutsy-security universe
deb http://security.ubuntu.com/ubuntu gutsy-security multiverse
deb-src http://security.ubuntu.com/ubuntu gutsy-security multiverse