Teste isso:
Abra um terminal
Pressione Ctrl + Alt + T
Execute:
sudo -i
nano /etc/apt/sources.list
No arquivo aberto.
Exclua o conteúdo.
Cole o seguinte:
deb http://us.archive.ubuntu.com/ubuntu/ utopic main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ utopic main restricted
deb http://us.archive.ubuntu.com/ubuntu/ utopic-updates main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ utopic-updates main restricted
deb http://us.archive.ubuntu.com/ubuntu/ utopic universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ utopic universe
deb http://us.archive.ubuntu.com/ubuntu/ utopic-updates universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ utopic-updates universe
deb http://us.archive.ubuntu.com/ubuntu/ utopic multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ utopic multiverse
deb http://us.archive.ubuntu.com/ubuntu/ utopic-updates multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ utopic-updates multiverse
deb http://us.archive.ubuntu.com/ubuntu/ utopic-backports main restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ utopic-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu utopic-security main restricted
# deb-src http://security.ubuntu.com/ubuntu utopic-security main restricted
deb http://security.ubuntu.com/ubuntu utopic-security universe
# deb-src http://security.ubuntu.com/ubuntu utopic-security universe
deb http://security.ubuntu.com/ubuntu utopic-security multiverse
# deb-src http://security.ubuntu.com/ubuntu utopic-security multiverse
deb http://archive.canonical.com/ubuntu utopic partner
# deb-src http://archive.canonical.com/ubuntu utopic partner
deb http://extras.ubuntu.com/ubuntu utopic main
# deb-src http://extras.ubuntu.com/ubuntu utopic main
deb http://us.archive.ubuntu.com/ubuntu/ utopic-proposed universe multiverse restricted main
Ctrl + O , salve o arquivo. Ctrl + X , perto do nano.
Continue em execução:
apt-get autoremove
apt-get clean
UNUSCONF=$(dpkg -l|grep "^rc"|awk '{print $2}')
apt-get remove --purge $UNUSCONF
NEWKERNEL=$(uname -r|sed 's/-*[a-z]//g'|sed 's/-386//g')
ADDKERNEL="linux-(image|headers|ubuntu-modules|restricted-modules)"
METAKERNEL="linux-(image|headers|restricted-modules)-(generic|i386|server|common|rt|xen)"
UNUSKERNELS=$(dpkg -l|awk '{print $2}'|grep -E $ADDKERNEL |grep -vE $METAKERNEL|grep -v $NEWKERNEL)
apt-get remove --purge $UNUSKERNELS
apt-get update
apt-get dist-upgrade
dpkg --configure -a
apt-get -f install
apt-get clean
reboot