Unable to install files with apt-get: "unable to locate package"

I'm having issues with my ubuntu server version 12.04 installed on a HP550 laptop, when i try sudo apt-get install , e.g apache2 it will not work, saying E: Unable to locate package apache2.

I have tried to look/edit the sources. but they will not work either the gedit command is broken too, i am trying gedit /etc/apt/sources.list for those wondering, is this a case of the computer network not configured properly? it downloaded a language pack easily enough in the installation though. how do i fix this? a prompt reply would be appreciated.