After executing the command sudo apt-get update why this error occured ?
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/raring/main/binary-amd64/Packages 404 Not Found [IP: 188.8.131.52 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/raring/universe/binary-amd64/Packages 404 Not Found [IP: 184.108.40.206 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
INFO The command [/bin/sh -c apt-get update] returned a non-zero code: 100