Whenever I write sudo apt-get update it does not work properly and shows following :
tusharmakkar08@tusharmakkar08-Satellite-C660 ~ $ sudo apt-get update
Ign http://archive.ubuntu.com nadia Release.gpg
Ign http://packages.medibuntu.org nadia Release.gpg
Ign http://archive.canonical.com nadia Release.gpg
Get:1 http://packages.linuxmint.com nadia Release.gpg [197 B]
Ign http://security.ubuntu.com nadia-security Release.gpg
Hit http://dl.google.com stable Release.gpg
Hit http://ppa.launchpad.net quantal Release.gpg
Ign http://archive.ubuntu.com nadia-updates Release.gpg
Hit http://archive.canonical.com quantal Release.gpg
Get:2 http://packages.linuxmint.com nadia Release [17.6 kB]
Get:3 http://security.ubuntu.com quantal-security Release.gpg [933 B]
Hit http://dl.google.com stable Release.gpg
Hit http://ppa.launchpad.net quantal Release
Hit http://packages.medibuntu.org quantal Release.gpg
Hit http://archive.ubuntu.com quantal Release.gpg
Ign http://archive.canonical.com nadia Release
Ign http://security.ubuntu.com nadia-security Release
Hit http://dl.google.com stable Release
Hit http://ppa.launchpad.net quantal/main Sources
Hit http://archive.canonical.com quantal Release
Get:4 http://security.ubuntu.com quantal-security Release [49.6 kB]
Hit http://dl.google.com stable Release
Get:5 http://archive.ubuntu.com quantal-updates Release.gpg [933 B]
Hit http://ppa.launchpad.net quantal/main i386 Packages
Ign http://packages.medibuntu.org nadia Release
Get:6 http://packages.linuxmint.com nadia/main i386 Packages [22.6 kB]
Hit http://dl.google.com stable/main i386 Packages
Hit http://packages.medibuntu.org quantal Release
Get:7 http://packages.linuxmint.com nadia/upstream i386 Packages [11.3 kB]
Hit http://archive.canonical.com quantal/partner i386 Packages
Get:8 http://packages.linuxmint.com nadia/import i386 Packages [44.0 kB]
Hit http://dl.google.com stable/main i386 Packages
Ign http://archive.ubuntu.com nadia Release
Ign http://archive.ubuntu.com nadia-updates Release
Hit http://archive.ubuntu.com quantal Release
Get:9 http://archive.ubuntu.com quantal-updates Release [49.6 kB]
Ign http://ppa.launchpad.net quantal/main Translation-en_IN
Ign http://ppa.launchpad.net quantal/main Translation-en
Get:10 http://security.ubuntu.com quantal-security/main i386 Packages [104 kB]
Hit http://packages.medibuntu.org quantal/free i386 Packages
Hit http://packages.medibuntu.org quantal/non-free i386 Packages
Ign http://dl.google.com stable/main Translation-en_IN
Err http://archive.canonical.com nadia/partner i386 Packages
404 Not Found [IP: 91.189.92.191 80]
Ign http://dl.google.com stable/main Translation-en
Ign http://archive.canonical.com nadia/partner Translation-en_IN
Ign http://dl.google.com stable/main Translation-en_IN
Ign http://archive.canonical.com nadia/partner Translation-en
Ign http://dl.google.com stable/main Translation-en
Ign http://archive.canonical.com quantal/partner Translation-en_IN
Get:11 http://security.ubuntu.com quantal-security/restricted i386 Packages [3,531 B]
Ign http://archive.canonical.com quantal/partner Translation-en
Get:12 http://security.ubuntu.com quantal-security/universe i386 Packages [45.8 kB]
Get:13 http://security.ubuntu.com quantal-security/multiverse i386 Packages [1,402 B]
Hit http://security.ubuntu.com quantal-security/main Translation-en
Hit http://security.ubuntu.com quantal-security/multiverse Translation-en
Hit http://archive.ubuntu.com quantal/main i386 Packages
Ign http://packages.linuxmint.com nadia/import Translation-en_IN
Hit http://archive.ubuntu.com quantal/restricted i386 Packages
Hit http://security.ubuntu.com quantal-security/restricted Translation-en
Hit http://archive.ubuntu.com quantal/universe i386 Packages
Hit http://archive.ubuntu.com quantal/multiverse i386 Packages
Ign http://packages.linuxmint.com nadia/import Translation-en
Hit http://security.ubuntu.com quantal-security/universe Translation-en
Ign http://packages.linuxmint.com nadia/main Translation-en_IN
Hit http://archive.ubuntu.com quantal/main Translation-en
Ign http://packages.linuxmint.com nadia/main Translation-en
Ign http://packages.linuxmint.com nadia/upstream Translation-en_IN
Hit http://archive.ubuntu.com quantal/multiverse Translation-en
Ign http://packages.linuxmint.com nadia/upstream Translation-en
Hit http://archive.ubuntu.com quantal/restricted Translation-en
Hit http://archive.ubuntu.com quantal/universe Translation-en
Get:14 http://archive.ubuntu.com quantal-updates/main i386 Packages [225 kB]
Get:15 http://archive.ubuntu.com quantal-updates/restricted i386 Packages [4,841 B]
Get:16 http://archive.ubuntu.com quantal-updates/universe i386 Packages [179 kB]
Get:17 http://archive.ubuntu.com quantal-updates/multiverse i386 Packages [10.8 kB]
Hit http://archive.ubuntu.com quantal-updates/main Translation-en
Hit http://archive.ubuntu.com quantal-updates/multiverse Translation-en
Hit http://archive.ubuntu.com quantal-updates/restricted Translation-en
Hit http://archive.ubuntu.com quantal-updates/universe Translation-en
Err http://packages.medibuntu.org nadia/free i386 Packages
404 Not Found
Err http://packages.medibuntu.org nadia/non-free i386 Packages
404 Not Found
Err http://security.ubuntu.com nadia-security/main i386 Packages
404 Not Found [IP: 91.189.92.200 80]
Ign http://packages.medibuntu.org nadia/free Translation-en_IN
Err http://security.ubuntu.com nadia-security/restricted i386 Packages
404 Not Found [IP: 91.189.92.200 80]
Err http://security.ubuntu.com nadia-security/universe i386 Packages
404 Not Found [IP: 91.189.92.200 80]
Ign http://packages.medibuntu.org nadia/free Translation-en
Err http://security.ubuntu.com nadia-security/multiverse i386 Packages
404 Not Found [IP: 91.189.92.200 80]
Ign http://security.ubuntu.com nadia-security/main Translation-en_IN
Ign http://packages.medibuntu.org nadia/non-free Translation-en_IN
Ign http://security.ubuntu.com nadia-security/main Translation-en
Ign http://security.ubuntu.com nadia-security/multiverse Translation-en_IN
Ign http://packages.medibuntu.org nadia/non-free Translation-en
Ign http://security.ubuntu.com nadia-security/multiverse Translation-en
Ign http://security.ubuntu.com nadia-security/restricted Translation-en_IN
Ign http://packages.medibuntu.org quantal/free Translation-en_IN
Ign http://security.ubuntu.com nadia-security/restricted Translation-en
Ign http://security.ubuntu.com nadia-security/universe Translation-en_IN
Ign http://security.ubuntu.com nadia-security/universe Translation-en
Ign http://security.ubuntu.com quantal-security/main Translation-en_IN
Ign http://security.ubuntu.com quantal-security/multiverse Translation-en_IN
Ign http://security.ubuntu.com quantal-security/restricted Translation-en_IN
Ign http://security.ubuntu.com quantal-security/universe Translation-en_IN
Ign http://packages.medibuntu.org quantal/free Translation-en
Ign http://packages.medibuntu.org quantal/non-free Translation-en_IN
Ign http://packages.medibuntu.org quantal/non-free Translation-en
Err http://archive.ubuntu.com nadia/main i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Err http://archive.ubuntu.com nadia/restricted i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Err http://archive.ubuntu.com nadia/universe i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Err http://archive.ubuntu.com nadia/multiverse i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Ign http://archive.ubuntu.com nadia/main Translation-en_IN
Ign http://archive.ubuntu.com nadia/main Translation-en
Ign http://archive.ubuntu.com nadia/multiverse Translation-en_IN
Ign http://archive.ubuntu.com nadia/multiverse Translation-en
Ign http://archive.ubuntu.com nadia/restricted Translation-en_IN
Ign http://archive.ubuntu.com nadia/restricted Translation-en
Ign http://archive.ubuntu.com nadia/universe Translation-en_IN
Ign http://archive.ubuntu.com nadia/universe Translation-en
Err http://archive.ubuntu.com nadia-updates/main i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Err http://archive.ubuntu.com nadia-updates/restricted i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Err http://archive.ubuntu.com nadia-updates/universe i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Err http://archive.ubuntu.com nadia-updates/multiverse i386 Packages
404 Not Found [IP: 91.189.92.202 80]
Ign http://archive.ubuntu.com nadia-updates/main Translation-en_IN
Ign http://archive.ubuntu.com nadia-updates/main Translation-en
Ign http://archive.ubuntu.com nadia-updates/multiverse Translation-en_IN
Ign http://archive.ubuntu.com nadia-updates/multiverse Translation-en
Ign http://archive.ubuntu.com nadia-updates/restricted Translation-en_IN
Ign http://archive.ubuntu.com nadia-updates/restricted Translation-en
Ign http://archive.ubuntu.com nadia-updates/universe Translation-en_IN
Ign http://archive.ubuntu.com nadia-updates/universe Translation-en
Ign http://archive.ubuntu.com quantal/main Translation-en_IN
Ign http://archive.ubuntu.com quantal/multiverse Translation-en_IN
Ign http://archive.ubuntu.com quantal/restricted Translation-en_IN
Ign http://archive.ubuntu.com quantal/universe Translation-en_IN
Ign http://archive.ubuntu.com quantal-updates/main Translation-en_IN
Ign http://archive.ubuntu.com quantal-updates/multiverse Translation-en_IN
Ign http://archive.ubuntu.com quantal-updates/restricted Translation-en_IN
Ign http://archive.ubuntu.com quantal-updates/universe Translation-en_IN
Fetched 771 kB in 1min 19s (9,715 B/s)
W: Failed to fetch http://archive.canonical.com/ubuntu/dists/nadia/partner/binary-i386/Packages 404 Not Found [IP: 91.189.92.191 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/nadia-security/main/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/nadia-security/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/nadia-security/universe/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/nadia-security/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://packages.medibuntu.org/dists/nadia/free/binary-i386/Packages 404 Not Found
W: Failed to fetch http://packages.medibuntu.org/dists/nadia/non-free/binary-i386/Packages 404 Not Found
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia/main/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia/universe/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia-updates/main/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia-updates/restricted/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia-updates/universe/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/nadia-updates/multiverse/binary-i386/Packages 404 Not Found [IP: 91.189.92.202 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.