Faça o seguinte para recriar seu sources.list
. Abra um terminal () e digite:
sudo su
Em seguida, recrie sua lista de fontes copiando e cole o seguinte bloco no terminal e pressione return uma vez.
cat > /etc/apt/sources.list << EOF
deb http://archive.ubuntu.com/ubuntu wily main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu wily main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu wily-updates main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu wily-updates main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu wily-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu wily-backports main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu wily-security main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu wily-security main restricted universe multiverse
deb http://archive.canonical.com/ubuntu wily partner
deb-src http://archive.canonical.com/ubuntu wily partner
EOF
Depois disso, simplesmente digite exit
para retornar ao seu modo de usuário normal. Todos devem estar se apresentando normalmente então.