Натискаш ALt+F2 и пишеш в конзолката
gksu nautilus
След което стартираш файловият мениджър с администраторски права
Отиваш във "файлова система">>etc>>apt, отваряш файла sources.list с текстов редактор
http://s19.postimg.org/5ldzyxq2b/sources_list.pngи копираш тази листа на мястото на съществуващата
#############################################################
################### OFFICIAL UBUNTU REPOS ###################
#############################################################
###### Ubuntu Main Repos
deb
http://de.archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse
deb-src
http://de.archive.ubuntu.com/ubuntu/ precise main restricted universe multiverse
###### Ubuntu Update Repos
deb
http://de.archive.ubuntu.com/ubuntu/ precise-security main restricted universe multiverse
deb
http://de.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src
http://de.archive.ubuntu.com/ubuntu/ precise-security main restricted universe multiverse
deb-src
http://de.archive.ubuntu.com/ubuntu/ precise-updates main restricted universe multiverse
deb-src
http://de.archive.ubuntu.com/ubuntu/ precise-backports main restricted universe multiverse
###### Ubuntu Partner Repo
deb
http://archive.canonical.com/ubuntu precise partner
deb-src
http://archive.canonical.com/ubuntu precise partner
###### Ubuntu Extras Repo
deb
http://extras.ubuntu.com/ubuntu precise main
deb-src
http://extras.ubuntu.com/ubuntu precise main
Запаметяваш промените, затваряш файла и файловият мениджър. Вече имаш нова листа.