A few weeks ago I installed ppa:ricotz/testing on Ubuntu 11.10. It worked fine then, but since a recent upgrade, trying to launch GTK applications results in lots of cryptic errors.
Can I revert all packages updated by ppa:ricotz/testing to the versions in the main Ubuntu repositories?
Yes. Assuming the PPA hasn't borked essential components of your system (like network connection, package management, and boot) it should be possible to restore your system to mainline Ubuntu packages.
First, get to a command-line. If your system is still usable enough to login and use an Ubuntu session, launch 'Terminal'. If not, press Ctrl-Alt-F1 (Ctrl-Alt-Fn-F1 if you have media keys), and login to the text prompt.
Now. First, finish any incomplete updates that may have been interrupted.
sudo dpkg --configure -a
If this repairs anything, it's possible no further repairs will be necessary; simply skip to the Finishing up step below. If nothing is repaired, the package integrity of your system is good, and PPAs may indeed be resposible.
First install ppa-purge...
sudo apt-get install ppa-purge
If you're using Ubuntu 10.04, you need to add lucid-backports to your software sources.
And then uninstall PPAs from your system like so, replacing ricotz/testing with the PPA you want to remove:
sudo ppa-purge ppa:ricotz/testing
(If you do not know what PPAs you have installed, you can check with cat /etc/apt/sources.list /etc/apt/sources.list.d/*.list | grep ppa. The PPA names correspond the unique portion of the URLs, such as ricotz/testing for ppa.launchpad.net/ricotz/testing/ubuntu/)
Finally, update your system and restart.
sudo apt-get update && sudo apt-get upgrade
sudo shutdown -r now
Hopefully you will reboot into a fixed Ubuntu.
