Revert system changes after apt-get upgrade on Linux Mint/Ubuntu

Question

I'm using Linux Mint 11 64 bit. I needed some packages to install newest software and found them in ubuntu repositories.

To do this I added

deb http://security.ubuntu.com/ubuntu oneiric-security main 
deb http://ubuntu.mirror.cambrium.nl/ubuntu/ oneiric main 

to my

/etc/apt/sources.list.

I made automatically sudo apt-get update + sudo apt-get upgrade and it installed ~900 packages from that repository (and removed some of my Mint too...). My system changed to Ubuntu-like dist, installed new graphical interface - probably GNOME3 (I liked my GNOME2 really much..). I am now unable to start GNOME2 at all.

Is there any way to undo this changes? I've removed that lines from sources.list, tried

sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade

but it didn't help.

Thanks.

Solution 1

No sorry, you are pretty screwed. You now have newer versions of most of the packages, so even if you remove the oneiric repo it will still opt to keep the new ones.

The best option is to backup and reinstall.

Solution 2

You can use ppa-purge - install with sudo apt-get install ppa-purge

See this article for more info

That will roll back your packages so it is safe to remove the repo and keep the software and your system wont blow up.

EDIT (based on user1131467's comment): for full-blown repositories, these answers will help, but it is much more manual:

https://askubuntu.com/a/3675/38901 and

https://superuser.com/a/195071/110574