I tried to used these commands at the root terminal:
sudo sed -i -e 's/archive.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.listsudo apt-get update && sudo apt-get dist-upgrade
The result is it could not find.
Then using the add/ remove GUI, I also could not load the Thunderbird to install.
I have very little Linux command text knowledge. How can I get and install Thunderbird into my old Ubuntu V9.xx?
You should try using the official thunderbird version provided by Mozilla, instead of the version in official Ubuntu repository provided by Canonical. At least on Ubuntu 9.04 and 9.10, the version in Ubuntu is not very good, and the upstream version is much better.