unable to download any software

I am not able to download even a single software from Ubuntu software center,even though I am connected to network.
when I used the command : sudo apt-get update && apt-get upgrade, I got the following errors:

Err http://security.ubuntu.com oneiric-security InRelease

Err http://security.ubuntu.com oneiric-security Release.gpg
Unable to connect to security.ubuntu.com:http: [IP: 91.189.92.151 80]
Err http://us.archive.ubuntu.com oneiric InRelease

Err http://us.archive.ubuntu.com oneiric-updates InRelease

Err http://us.archive.ubuntu.com oneiric-backports InRelease

Err http://us.archive.ubuntu.com oneiric Release.gpg
Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.92.193 80]
Err http://us.archive.ubuntu.com oneiric-updates Release.gpg
Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.92.193 80]
Err http://us.archive.ubuntu.com oneiric-backports Release.gpg
Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.92.193 80]
Reading package lists... Done
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric/InRelease

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

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric-backports/InRelease

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

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/oneiric-security/Release.gpg Unable to connect to security.ubuntu.com:http: [IP: 91.189.92.151 80]

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric/Release.gpg Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.92.193 80]

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric-updates/Release.gpg Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.92.193 80]

W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric-backports/Release.gpg Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.92.193 80]

W: Some index files failed to download. They have been ignored, or old ones used instead.
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?

is there anyone who can get me out of this ?????

unable to download anything in ubuntu 11.02

someone please help me out

only one package manager at a time

make shore you are using only one package manager that includes terminal ,.its telling you that you have a program already accessing packages.