Ubuntu 9.04 is no longer supported however old-release repositories are available to enable the user to install software and apply any updates that were in place prior to its end of life date
https://lists.ubuntu.com/archives/ubuntu-announce/2010-September/000137.html
Open the Terminal and submit the following command:
sudo gedit /etc/apt/sources.list
The repository window will open. Delete all the default Jaunty repositories and replace them with
deb http://old-releases.ubuntu.com/ubuntu/ jaunty main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ jaunty-updates main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ jaunty-security main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ jaunty-backports main restricted universe multiverse
deb http://old-releases.ubuntu.com/ubuntu/ jaunty-proposed main restricted universe multiverse
Save these changes in the repository window and close
Back in the Terminal enter the following command:
sudo apt-get update
Close Terminal.
All the Ubuntu Jaunty should now work and there may be some updates to apply that were released prior to the end of date.
LUg.