Teste este procedimento:
Primeiro: você precisa atualizar o sistema.
Abra um terminal
Pressione Ctrl + Alt + T
Execute:
sudo -i
apt-get update
apt-get dist-upgrade
Reinicialize seu sistema para concluir a instalação de atualizações e para atualizar para a nova versão disponível:
Abra um terminal
Pressione Ctrl + Alt + T
Execute:
sudo -i
nano /etc/apt/sources.list
No arquivo aberto, exclua o conteúdo e cole isso:
deb http://ar.archive.ubuntu.com/ubuntu/ trusty main restricted
# deb-src http://ar.archive.ubuntu.com/ubuntu/ trusty main restricted
deb http://ar.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
# deb-src http://ar.archive.ubuntu.com/ubuntu/ trusty-updates main restricted
deb http://ar.archive.ubuntu.com/ubuntu/ trusty universe
# deb-src http://ar.archive.ubuntu.com/ubuntu/ trusty universe
deb http://ar.archive.ubuntu.com/ubuntu/ trusty-updates universe
# deb-src http://ar.archive.ubuntu.com/ubuntu/ trusty-updates universe
deb http://ar.archive.ubuntu.com/ubuntu/ trusty multiverse
# deb-src http://ar.archive.ubuntu.com/ubuntu/ trusty multiverse
deb http://ar.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
# deb-src http://ar.archive.ubuntu.com/ubuntu/ trusty-updates multiverse
deb http://ar.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
# deb-src http://ar.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu trusty-security main restricted
# deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted
deb http://security.ubuntu.com/ubuntu trusty-security universe
# deb-src http://security.ubuntu.com/ubuntu trusty-security universe
deb http://security.ubuntu.com/ubuntu trusty-security multiverse
# deb-src http://security.ubuntu.com/ubuntu trusty-security multiverse
deb http://archive.canonical.com/ubuntu trusty partner
# deb-src http://archive.canonical.com/ubuntu trusty partner
deb http://extras.ubuntu.com/ubuntu trusty main
# deb-src http://extras.ubuntu.com/ubuntu trusty main
deb http://ar.archive.ubuntu.com/ubuntu/ trusty-proposed universe multiverse restricted main
Ctrl + O , salve o arquivo. Ctrl + X , perto do nano.
Continue a execução em um terminal:
sudo -i
apt-get clean
apt-get update
apt-get dist-upgrade
apt-get autoremove
apt-get -f install
dpkg --configure -a
apt-get clean
reboot