1.备份原来的源文件

cd/etc/apt
cpsources.listsources.list.00

2.将源文件清空后更新为网易的源

visources.list

debhttp://mirrors.163.com/ubuntu/trustymainrestricteduniversemultiverse
debhttp://mirrors.163.com/ubuntu/trusty-securitymainrestricteduniversemultiverse
debhttp://mirrors.163.com/ubuntu/trusty-updatesmainrestricteduniversemultiverse
debhttp://mirrors.163.com/ubuntu/trusty-proposedmainrestricteduniversemultiverse
debhttp://mirrors.163.com/ubuntu/trusty-backportsmainrestricteduniversemultiverse
deb-srchttp://mirrors.163.com/ubuntu/trustymainrestricteduniversemultiverse
deb-srchttp://mirrors.163.com/ubuntu/trusty-securitymainrestricteduniversemultiverse
deb-srchttp://mirrors.163.com/ubuntu/trusty-updatesmainrestricteduniversemultiverse
deb-srchttp://mirrors.163.com/ubuntu/trusty-proposedmainrestricteduniversemultiverse
deb-srchttp://mirrors.163.com/ubuntu/trusty-backportsmainrestricteduniversemultiverse

3.更新系统

apt-getupdate
apt-getupgrade

最后附上阿里云的源：

debhttp://mirrors.aliyun.com/ubuntu/trustymainrestricteduniversemultiverse
debhttp://mirrors.aliyun.com/ubuntu/trusty-securitymainrestricteduniversemultiverse
debhttp://mirrors.aliyun.com/ubuntu/trusty-updatesmainrestricteduniversemultiverse
debhttp://mirrors.aliyun.com/ubuntu/trusty-proposedmainrestricteduniversemultiverse
debhttp://mirrors.aliyun.com/ubuntu/trusty-backportsmainrestricteduniversemultiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/trustymainrestricteduniversemultiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/trusty-securitymainrestricteduniversemultiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/trusty-updatesmainrestricteduniversemultiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/trusty-proposedmainrestricteduniversemultiverse
deb-srchttp://mirrors.aliyun.com/ubuntu/trusty-backportsmainrestricteduniversemultiverse