Ubuntu 12.10 (a.k.a. Quantal) has reached "End of Life" and is no longer supported by Ubuntu. You are strongly encouraged to upgrade to a newer release so that you continue to receive security updates.
If you need to continue using it at least temporarily, we have set up a mirror of the old repository at mirrors.digitalocean.com/ubuntu-old You can edit your
/etc/apt/sources.list file to point to that repository.