Default themes are gone, windows look ugly

I have recently made an upgrade from 11.10 to 12.04. Everything went fine, except the theme I used to have, Hope-DT, was having the fonts coloured white. So, yesterday, trying to find an updated version of Hope Theme, I have installed this .deb (which was suppose to fix the problems): i386 build of hope-gtk-theme 0.0.2-precise in ubuntu precise RELEASE

Now, I have found myself with a broken desktop...it's like GTK3. Firstly I can't find the default theme Ambience anymore. No tool shows it (System Settings/Appearence nor MyUnity nor Advanced Settings). And I have all over crappy windows and buttons. Check out the screenshots:

So now after nice Unity3D smooth feeling, I am stuck with this kind of windows. Is there a way to reinstall the default themes again? Or to somehow fix GTK3.

To make things worse, I thought it would be a good idea to restore my system to a back-up I made with duplicity yesterday. It was a good opportunity to use the tool, because I am backing up for some time now, and I never got my hands to make a restore.

The restore crashed in the middle (Ubuntu 12.04 encountered an error). And since then...I keep getting errors, and the system tries to send infos to Ubuntu but doesn't seem to be able to:

I am pretty disappointed that I did not manage to make a successful back-up/restore...why do we even have the tool then... At any rate, this issue may be related to the fact that I might have some gtk files missing.

I am pretty close to make a full reinstall, but it pains me to know that all of this might have started because I wanted to fix my theme :(

Any way to restore the default theme? Or Gtk? Maybe that solves some problems.

Solution 1:

Try reinstalling the light-themes package, This package includes both default Ubuntu themes (Ambiance and Radiance).

Hit Alt+Ctrl+T to open terminal and run following commands:

sudo apt-get autoremove --purge  light-themes
sudo apt-get install  light-themes

Then restart your system!