How to repair a broken Ubuntu Desktop installation - Karmic Koala

While tracking visitors to my site, I was surprised to see visitors coming to my very old post about repairing Ubuntu installation. I had had some problem in my Ubuntu 7.04 installation some time ago & I had managed to fix it by trial and error. I hoped that my post would help others facing the same problem.

I was surprised as I wondered why people were still using Ubuntu 7.04. Till the time I decided to return to testing Ubuntu i.e. I had lost touch with Ubuntu and Linux in general as my job changed and family grew. Very recently another change happened that allowed me some free time to explore technology. So I started with my favorite pastime of downloading and test driving latest versions of Fedora and Ubuntu.

I had heard that Ubuntu will provide support for inplace upgrade ala Windows versus the destructive upgrade that Linux had though I had never tried it. I had downloaded the latest version of Ubuntu 9.04 - Jaunty Jackalope and installed it on a virtual instance and then again got busy in my work. After a while, like 4-5 weeks later I found out that the next version 9.10 - Karmic Koala is out and noticed that the inplace upgrade option is available so I decided to give the in-place upgrade a try.

Overall the upgrade process was easy (though time consuming) but the real surprise was after the installation was over. Once the OS restarted, all I could get was flashing screen showing login.

It did not accept keyboard input gracefully & basically I was unable to login. I tried researching this issue on the internet with no success. My initial thought was that the kernel was corrupt & I was thinking about reinstalling the OS from scratch. However, I decided to try rolling back the kernel in the hope that maybe that was bad and rolling back would do the trick.

I booted up the OS, went into Grub menu and chose recovery mode. 

I tried a couple of things here before I found a surprising thing. If I chose "Resume normal boot" here, I was able to get a stable command line based login prompt. So I logged in tried a few things. However not being a Linux guru was not able to make any headway so again resorted back to the internet to search for fresh lead.

One of the forum mentioned something about the display settings in passing and that lit a light in my head. I logged back in & looked at the xorg.conf file and saw that was messed up.

Section "Device"
Identifier "Configured Video Device"
EndSection

Section "Monitor"
Identifier "Configured Monitor"
EndSection

Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
EndSection

I took a chance and renamed the file to xorg.conf.corrupt and rebooted.

mukul@linux9:/etc/X11$ sudo mv xorg.conf xorg.conf.corrupt

I was very happy to find that Ubuntu booted happily in GUI mode. You can choose any name you want or even delete this file. But normally I recommend keeping a backup just in case so my recommendation would be to rename it or move it to some other location.