upgrading from 12.04.5 to 14.04

[orky7]

hello i am trying to upgrade from 12.04.5( get this from lsb_release -a) to 14.04. The system is updated there is no package in the update manager. when i click upgrade then in the step "setting the new software channel" it gives an error msg:

W:Failed to fetch http:// archive.ubuntu.com/ubuntu/dists/trusty/universe/source/Sources 404 Not Found [IP: 91.189.88.161 80]
, W:Failed to fetch http:// archive.ubuntu.com/ubuntu/dists/trusty/universe/binary-amd64/Packages 404 Not Found [IP: 91.189.88.161 80]
, W:Failed to fetch http:// archive.ubuntu.com/ubuntu/dists/trusty/universe/binary-i386/Packages 404 Not Found [IP: 91.189.88.161 80]
, E:Some index files failed to download. They have been ignored, or old ones used instead.

please help me in upgrading my system. if you need any more info please ask for it.

thank you

my source.list is

# deb cdrom:[Ubuntu 12.04.2 LTS _Precise Pangolin_ - Release amd64 (20130213)]/ dists/precise/main/binary-i386/

# deb cdrom:[Ubuntu 12.04.2 LTS _Precise Pangolin_ - Release amd64 (20130213)]/ dists/precise/restricted/binary-i386/
# deb cdrom:[Ubuntu 12.04.2 LTS _Precise Pangolin_ - Release amd64 (20130213)]/ precise main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu precise main restricted
deb-src http://archive.ubuntu.com/ubuntu precise main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu precise-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu precise-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu precise universe
deb-src http://archive.ubuntu.com/ubuntu precise universe
deb http://archive.ubuntu.com/ubuntu precise-updates universe
deb-src http://archive.ubuntu.com/ubuntu precise-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://archive.ubuntu.com/ubuntu precise multiverse
deb-src http://archive.ubuntu.com/ubuntu precise multiverse
deb http://archive.ubuntu.com/ubuntu precise-updates multiverse
deb-src http://archive.ubuntu.com/ubuntu precise-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu precise-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu precise-backports main restricted universe multiverse

deb http://archive.ubuntu.com/ubuntu precise-security main restricted
deb-src http://archive.ubuntu.com/ubuntu precise-security main restricted
deb http://archive.ubuntu.com/ubuntu precise-security universe
deb-src http://archive.ubuntu.com/ubuntu precise-security universe
deb http://archive.ubuntu.com/ubuntu precise-security multiverse
deb-src http://archive.ubuntu.com/ubuntu precise-security multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu precise partner
# deb-src http://archive.canonical.com/ubuntu precise partner

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu precise main
deb-src http://extras.ubuntu.com/ubuntu precise main