(This is an optional step, i prefer doing it like this so as to keep things clean!)
First of all go to Synaptic and completely remove the application (Mark for Complete Removal)
Remove all versions of the program including the ones you installed manually. Then look for any related packages on the left pane (Automatic Remove). Purge them also.
(Adding Repositories is kinda tricky especially if you haven't done so before, so if you don't feel comfortable about doing something, ask first and don't do hasty moves)
First navigate the page. See what you can understand from it. Look around. Maybe you won't need help at all
click on "Not using Ubuntu 9.10 (Karmic)?"
Extra info will be displayed. Choose from the dropdown box "Jaunty 9.04"
Open "Software Sources" from the menu (System - Administration - Software Sources)
Go to the tab "Third Party Software". Click on "Add"
Copy the first line of the PPA. You'll find it is:
Then repeat once again for the second line:
deb http://ppa.launchpad.net/mscore-ubuntu/mscore-stable/ubuntu jaunty main
Then you have to import the key.
deb-src http://ppa.launchpad.net/mscore-ubuntu/mscore-stable/ubuntu jaunty main
open a terminal and enter
It will return sth like key imported..so you can skip the next step
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3A258030
ALTERNATIVE METHOD (A lot more time consuming
Copy the above to your text editor and save it on your desktop as mscore.key
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: SKS 1.0.10
-----END PGP PUBLIC KEY BLOCK-----
Then on Software Sources click on the "Authentication" tab and then click on the "Add Key" button.
Navigate to your desktop (/home/Username/Desktop) and import the file you created previously (mscore.key) and hit close
It will ask you to update the repositories, so update!
After all this you can once again fire up synaptic and install the application again. I think you will find the version is 0.9.5