Mientras ejecuta elsudo apt-get update en ubuntu 17.04 Zesty Zapus, obtengo el siguiente error. He publicado en las líneas de error. Quería instalar bibliotecas de python como matplotlib y tkinter que no se pudieron instalar porque el comando anterior no se ejecutó correctamente. Por favor sugiérame qué hacer.

Err:9 http://security.ubuntu.com/ubuntu zesty-security/main amd64 Packages
  404  Not Found [IP: 2001:67c:1560:8001::14 80]
Err:25 http://in.archive.ubuntu.com/ubuntu zesty/main i386 Packages
  404  Not Found [IP: 2001:67c:1360:8001::21 80]
Err:81 http://in.archive.ubuntu.com/ubuntu zesty-updates/main amd64 Packages
  404  Not Found [IP: 2001:67c:1360:8001::21 80]
Err:113 http://in.archive.ubuntu.com/ubuntu zesty-backports/main amd64 Packages
  404  Not Found [IP: 2001:67c:1360:8001::21 80]
Reading package lists... Done
W: The repository 'http://security.ubuntu.com/ubuntu zesty-security Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://in.archive.ubuntu.com/ubuntu zesty Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://in.archive.ubuntu.com/ubuntu zesty-updates Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://in.archive.ubuntu.com/ubuntu zesty-backports Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://security.ubuntu.com/ubuntu/dists/zesty-security/main/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1560:8001::14 80]
E: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/zesty/main/binary-i386/Packages  404  Not Found [IP: 2001:67c:1360:8001::21 80]
E: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/zesty-updates/main/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1360:8001::21 80]
E: Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/zesty-backports/main/binary-amd64/Packages  404  Not Found [IP: 2001:67c:1360:8001::21 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.