as the root user edit the file /etc/apt/sources.list and remove all the text inside the file and then add these lines:
deb http://us.archive.ubuntu.com/ubuntu/ precise main deb-src http://us.archive.ubuntu.com/ubuntu/ precise main deb http://us.archive.ubuntu.com/ubuntu/ precise-updates main deb-src http://us.archive.ubuntu.com/ubuntu/ precise-updates mainCongratulations you just used a different repo!! (although using non-free software defeats the point of using Trisquel)
