问题：
root@ubuntu:/etc/apt# apt-get update
Ign http://us.archive.ubuntu.com wily InRelease
Ign http://security.ubuntu.com wily-security InRelease
Ign http://us.archive.ubuntu.com wily-updates InRelease
Ign http://security.ubuntu.com wily-security Release.gpg
Ign http://us.archive.ubuntu.com wily-backports InRelease
Ign http://security.ubuntu.com wily-security Release
Ign http://us.archive.ubuntu.com wily Release.gpg
Ign http://us.archive.ubuntu.com wily-updates Release.gpg
Ign http://security.ubuntu.com wily-security/main Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports Release.gpg
Ign http://security.ubuntu.com wily-security/restricted Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily Release
Ign http://security.ubuntu.com wily-security/universe Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates Release
Ign http://security.ubuntu.com wily-security/multiverse Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports Release
Ign http://us.archive.ubuntu.com wily/main Sources/DiffIndex
Ign http://security.ubuntu.com wily-security/main amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/restricted Sources/DiffIndex
Ign http://security.ubuntu.com wily-security/restricted amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/universe Sources/DiffIndex
Ign http://security.ubuntu.com wily-security/universe amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/multiverse Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily/main amd64 Packages/DiffIndex
Ign http://security.ubuntu.com wily-security/multiverse amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/restricted amd64 Packages/DiffIndex
Ign http://security.ubuntu.com wily-security/main i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/universe amd64 Packages/DiffIndex
Ign http://security.ubuntu.com wily-security/restricted i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/multiverse amd64 Packages/DiffIndex
Ign http://security.ubuntu.com wily-security/universe i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/main i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/restricted i386 Packages/DiffIndex
Ign http://security.ubuntu.com wily-security/multiverse i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/universe i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily/multiverse i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/main Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/restricted Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/universe Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/multiverse Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/main amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/restricted amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/universe amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/multiverse amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/main i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/restricted i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/universe i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-updates/multiverse i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/main Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/restricted Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/universe Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/multiverse Sources/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/main amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/restricted amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/universe amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/multiverse amd64 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/main i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/restricted i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/universe i386 Packages/DiffIndex
Ign http://us.archive.ubuntu.com wily-backports/multiverse i386 Packages/DiffIndex
Ign http://security.ubuntu.com wily-security/main Translation-en_US
Ign http://security.ubuntu.com wily-security/main Translation-en
Ign http://security.ubuntu.com wily-security/multiverse Translation-en_US
Ign http://security.ubuntu.com wily-security/multiverse Translation-en
Ign http://security.ubuntu.com wily-security/restricted Translation-en_US
Ign http://security.ubuntu.com wily-security/restricted Translation-en
Ign http://security.ubuntu.com wily-security/universe Translation-en_US
Ign http://security.ubuntu.com wily-security/universe Translation-en
Err http://security.ubuntu.com wily-security/main Sources
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/restricted Sources
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/universe Sources
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/multiverse Sources
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/main amd64 Packages
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/restricted amd64 Packages
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/universe amd64 Packages
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/multiverse amd64 Packages
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/main i386 Packages
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/restricted i386 Packages
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/universe i386 Packages
404 Not Found [IP: 91.189.91.26 80]
Err http://security.ubuntu.com wily-security/multiverse i386 Packages
404 Not Found [IP: 91.189.91.26 80]
解决办法：
Ubuntu 的旧版本 已经停止支持,但可以使用old-releases源了,先备份源列表文件:
sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup
sudo gedit /etc/apt/sources.list
把里面的内容替换为以下内容:
deb http://old-releases.ubuntu.com/ubuntu/ natty main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-security main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-updates main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-proposed main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ natty main restricted universe multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ natty-security main restricted universe multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ natty-updates main restricted universe multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ natty-proposed main restricted universe multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse
重载源列表,使配置生效:
apt-get update
亲测可用