Are you getting these errors?
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/main/binary-amd64/Packages 404 Not Found [IP: 91.189.88.142 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-amd64/Packages 404 Not Found [IP: 91.189.88.142 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/universe/binary-amd64/Packages 404 Not Found [IP: 91.189.88.142 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found [IP: 91.189.88.142 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.88.142 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/precise/universe/binary-i386/Packages 404 Not Found [IP: 91.189.88.142 80]
SOLUTION
Try changing the domain names in /etc/apt/sources.list from
archive.ubuntu.com
security.ubuntu.com
to
old-releases.ubuntu.com
FINAL RESULT
Example content of /etc/apt/sources.list:
deb http://old-releases.ubuntu.com/ubuntu precise main restricted universe
deb http://old-releases.ubuntu.com/ubuntu precise-updates main restricted universe
deb http://old-releases.ubuntu.com/ubuntu precise-security main restricted universe multiverse
deb http://old-releases.canonical.com/ubuntu precise partner
