/etc/apt/sources.list

add these lines:

Code: Select all

deb http://archive.debian.org/debian/ jessie main non-free contrib
deb-src http://archive.debian.org/debian/ jessie main non-free contrib
deb http://archive.debian.org/debian-security/ jessie/updates main non-free contrib
deb-src http://archive.debian.org/debian-security/ jessie/updates main non-free contrib

and run

apt-get update

If you get an error about keyrings, just install it

apt-get install debian-archive-keyring

and run

apt-get update