I have made an epic fail also....

[rajibando]

Because your lines are wrong!
I will give you a general direction. Look at sources.list, first line. See what is the Debian stable Version for the Knoppix version? It is the stock version.
Go to Debian site. See the series of versions: Lenny, Wheezy, Jessie, ...
For example, if Lenny, Then replace stable with Lenny, unstable with Wheezy, Jessie with ...
I hope you understand.
If something has been archived, replace the sources line to direct to the archived version.
Just use common sense, and no complicated ideas.

P.S. Please don't post too much of snapshots. Just post what you are asked to post.