No desktop after apt upgrade from 11 to 14

[frantsch]

I upgraded from linux mint 11 to 14 (32 bit) using the instructions given in http://forums.linuxmint.com/viewforum.php?f=90 and using 'nadia' and 'precise' when editing the sources.list file. Everything went well, apt-get update, apt-get dist-upgrade, as well as apt-get upgrade executed without any error messages.
After reboot however, the desktop environment does not start up and shows a black screen only. When I try the recovery mode and choose to get to the command line, I am asked for the root password. However it seems to have changed, my former root password would not work. How can I get the system running again?

[remoulder]

How can I get the system running again?

Mint does not support in place upgrades especially between 4 versions, you follow other users suggestions at your own risk. A fresh install is recommended.

[frantsch]

Thank you for your hint! But how may I get all the personal data of the users saved before installing freshly?

[remoulder]

how may I get all the personal data

See http://community.linuxmint.com/tutorial/view/2

[frantsch]

Sorry, but this does not help in my case. As I said, I am no more able to obtain any desktop on my system in order to do any backup or so, and not even a shell command line, since my root password does not fit any more due to the upgrade process. Is there any way to boot by cd and mount the system harddrive as well as an external drive in order to copy the data from the users' system drive?
I am not very familiar with linux, any help is appreciated since it is very important for me to safe all users' data!

[remoulder]

Then I suggest you boot from a live disc or usb, which I guess you'll need to make on another machine or buy, and use that to backup the data on your hard drive before re-installing. Good luck.

[frantsch]

Thank you, I will give it a try. I am able to access the system drives when booting from live dvd. Will it be sufficient to backup the /home to an external drive and to restore it after fresh installation? Will I have to create the former users first or are they created automatically by restoring their subdirectories under /home?

[remoulder]

No you can't just restore the home, you will first have to create the user in the new install. Also do not just restore the home, this is partially the reason why you can't upgrade in place as config files from previous version in home are not compatible. In general, you should only restore your actual data, documents, pictures, etc and browser and email folders (.mozilla and .thunderbird for FF and TB). The safest way to do it is to login as your new user after install to create the home structure then copy the data from the backup into the same folders in the new home, e.g. contents of Documents in backup to new home's Documents. This way the permissions should be correct.