cp -p /etc/apt/sources.list /etc/apt/sources.list_backup
nano /etc/apt/sources.list

deb http://lv.archive.ubuntu.com/ubuntu dapper main restricted universe multiverse

## Add comments (##) in front of any line to remove it from being checked.
## Use the following sources.list at your own risk.

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

## MAJOR BUG FIX UPDATES produced after the final release
deb http://archive.ubuntu.com/ubuntu dapper-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu dapper-updates main restricted universe multiverse

## UBUNTU SECURITY UPDATES
deb http://security.ubuntu.com/ubuntu dapper-security main restricted universe multiverse
deb-src http://security.ubuntu.com/ubuntu dapper-security main restricted universe multiverse

## BACKPORTS REPOSITORY (Unsupported. May contain illegal packages. Use at own risk.)
deb http://archive.ubuntu.com/ubuntu dapper-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu dapper-backports main restricted universe multiverse

## PLF REPOSITORY (Unsupported. May contain illegal packages. Use at own risk.)
deb http://packages.freecontrib.org/plf dapper free non-free
deb-src http://packages.freecontrib.org/plf dapper free non-free

## CANONICAL COMMERCIAL REPOSITORY (Hosted on Canonical servers, not Ubuntu
## servers. RealPlayer10, Opera and more to come.)
deb http://archive.canonical.com/ubuntu dapper-commercial main