Not able to install softwares from Ubuntu 11.04 software centre

I tried to install software from Ubuntu 11.04 Software center but I could not.
Please help me.I am a beginner.
I tried some commands....

rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo fuser -vvv /var/lib/dpkg/lock
[sudo] password for rashu:
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=11.04
DISTRIB_CODENAME=natty
DISTRIB_DESCRIPTION="Ubuntu 11.04"
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ uname -a
Linux Compaq-Presario-CQ42-Notebook-PC 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:50 UTC 2011 i686 i686 i386 GNU/Linux
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo rm /var/lib/apt/lists/lock
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo cp -arf /var/lib/dpkg /var/lib/dpkg.backup
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo cp /var/lib/dpkg/status-old /var/lib/dpkg/status
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo cp /var/lib/dpkg/available-old /var/lib/dpkg/available
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo rm -rf /var/lib/dpkg/updates/*
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo rm -rf /var/lib/apt/lists
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo rm /var/cache/apt/*.bin
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo mkdir /var/lib/apt/lists
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo mkdir /var/lib/apt/lists/partial
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ LANG=C;sudo apt-get clean
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ LANG=C;sudo apt-get autoclean
Reading package lists... Done
Building dependency tree
Reading state information... Done
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ LANG=C;sudo apt-get --purge autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
You might want to run 'apt-get -f install' to correct these.
The following packages have unmet dependencies:
 language-pack-de : Depends: language-pack-de-base (>= 1:11.04+20110421) but it is not installable
 language-pack-es : Depends: language-pack-es-base (>= 1:11.04+20110421) but it is not installable
 language-pack-pt : Depends: language-pack-pt-base (>= 1:11.04+20110421) but it is not installable
 language-pack-xh : Depends: language-pack-xh-base (>= 1:11.04+20110421) but it is not installable
E: Unmet dependencies. Try using -f.
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ LANG=C;sudo apt-get update -o APT::Cache-Limit=25165824
Err http://archive.ubuntu.com natty InRelease

Err http://archive.ubuntu.com natty-updates InRelease

Err http://archive.ubuntu.com natty-security InRelease

Err http://archive.canonical.com natty InRelease

Err http://archive.ubuntu.com natty Release.gpg
  Could not resolve 'archive.ubuntu.com'
Err http://archive.ubuntu.com natty-updates Release.gpg
  Could not resolve 'archive.ubuntu.com'
Err http://archive.canonical.com natty Release.gpg
  Could not resolve 'archive.canonical.com'
Err http://archive.ubuntu.com natty-security Release.gpg
  Could not resolve 'archive.ubuntu.com'
Err http://extras.ubuntu.com natty InRelease

Err http://extras.ubuntu.com natty Release.gpg
  Could not resolve 'extras.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty/InRelease

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-updates/InRelease

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-security/InRelease

W: Failed to fetch http://archive.canonical.com/ubuntu/dists/natty/InRelease

W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/InRelease

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty/Release.gpg Could not resolve 'archive.ubuntu.com'

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-updates/Release.gpg Could not resolve 'archive.ubuntu.com'

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-security/Release.gpg Could not resolve 'archive.ubuntu.com'

W: Failed to fetch http://archive.canonical.com/ubuntu/dists/natty/Release.gpg Could not resolve 'archive.canonical.com'

W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/Release.gpg Could not resolve 'extras.ubuntu.com'

W: Some index files failed to download. They have been ignored, or old ones used instead.
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo dpkg --clear-avail
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ sudo dpkg --configure -a
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ LANG=C;sudo apt-get -f install
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following packages will be REMOVED:
  language-pack-de language-pack-es language-pack-pt language-pack-xh
0 upgraded, 0 newly installed, 4 to remove and 0 not upgraded.
After this operation, 147 kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ...
dpkg: warning: files list file for package `reiserfsprogs' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `language-pack-pt' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `ubiquity' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `language-pack-de' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `python-pyicu' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `ubiquity-frontend-gtk' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `apt-clone' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `libdebian-installer4' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `rdate' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `language-pack-xh' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `libdebconfclient0' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `language-pack-zh-hans-base' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `libcheese-gtk18' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `ubiquity-casper' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `dpkg-repack' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `language-pack-es' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `ubiquity-ubuntu-artwork' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `archdetect-deb' missing, assuming package has no files currently installed.

dpkg: warning: files list file for package `language-pack-zh-hans' missing, assuming package has no files currently installed.
(Reading database ... 129643 files and directories currently installed.)
Removing language-pack-de ...
Removing language-pack-es ...
Removing language-pack-pt ...
Removing language-pack-xh ...
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ LANG=C;sudo apt-get --fix-missing install
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
rashu@Compaq-Presario-CQ42-Notebook-PC:~$ LANG=C;sudo apt-get update -o APT::Cache-Limit=25165824 && sudo apt-get dist-upgrade
Err http://extras.ubuntu.com natty InRelease

Err http://archive.ubuntu.com natty InRelease

Err http://archive.ubuntu.com natty-updates InRelease

Err http://archive.ubuntu.com natty-security InRelease

Err http://archive.canonical.com natty InRelease

Err http://extras.ubuntu.com natty Release.gpg
  Could not resolve 'extras.ubuntu.com'
Err http://archive.ubuntu.com natty Release.gpg
  Could not resolve 'archive.ubuntu.com'
Err http://archive.ubuntu.com natty-updates Release.gpg
  Could not resolve 'archive.ubuntu.com'
Err http://archive.canonical.com natty Release.gpg
  Could not resolve 'archive.canonical.com'
Err http://archive.ubuntu.com natty-security Release.gpg
  Could not resolve 'archive.ubuntu.com'
Reading package lists... Done
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty/InRelease

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-updates/InRelease

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-security/InRelease

W: Failed to fetch http://archive.canonical.com/ubuntu/dists/natty/InRelease

W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/InRelease

W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/Release.gpg Could not resolve 'extras.ubuntu.com'

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty/Release.gpg Could not resolve 'archive.ubuntu.com'

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-updates/Release.gpg Could not resolve 'archive.ubuntu.com'

W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/natty-security/Release.gpg Could not resolve 'archive.ubuntu.com'

W: Failed to fetch http://archive.canonical.com/ubuntu/dists/natty/Release.gpg Could not resolve 'archive.canonical.com'

W: Some index files failed to download. They have been ignored, or old ones used instead.
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
rashu@Compaq-Presario-CQ42-Notebook-PC:~$