where and how did you disable them?
it still sounds like it would be helpful to see what is in your sources.list file:
i was able to double-click mine and it opened with a text editor. if you are trying to open it in a terminal, you can use
cat /etc/apt/sources.list.
it also sounds like it might be helpful to see what your /etc/lsb-release file says. that one also opens with a double-click or cat.
can you copy and paste the error message you are getting?