I've just installed lubuntu 12.04 on an Acer aspire one netbook. I've noticed that although chromium-browser is installed, it doesn't come with a flash-player. I tried to install it using
sudo apt-get install flashplugin-installer
but I get the error
E: Unable to locate package flashplugin-installer
I also tried to install some other basic packages like gedit, deluge, kate, geany but I get the same error. Then I tried to update all repositories using
sudo apt-get update && sudo apt-get upgrade
but while it's running there are some errors like
Err http://gr.archive.ubuntu.com quantal-updates/main Sources
404 Not Found
or
W: Failed to fetch http://gr.archive.ubuntu.com/ubuntu/dists/quantal/restricted/source/Sources 404 Not Found
Why is this happening? I've checked my internet connection and it's fine. I also tried to install chrome using GDebi package installer` but I get an error
Dependency is not satisfiable : libnns3(>=3.14.3)
I believe that somehow I cannot see the repositories. What can I do to fix this?