Recovering a Ubuntu 10.10 installation
 

A friend of mine was upgrading his 10.10 distribution to 11.04, during the process a power cut caused interrupt and no he is unable to get in to his system. after the ubuntu screen he goes to the prompt, where he sees nothing but this

Is there any possible way to recover this system

A little more information would be a big help here.

What is the hardware? How was this upgrade being done? Is the OS installed on one partition or more?

If you have a Live CD (any recent one from any Linux distro) it would be a good idea to take a look at the files on the box and make sure they are there (probably). Then back them up, to CD/DVDs, by making an other partition on the HDD and putting them there, putting them on a thumb drive.

I would then try to use an install disk for 11.04 to do the rest of the job. No matter how the OS is now installed you need to choose Manual Partitioning. I believe Ubuntu calls this option "Something Else" to confuse the user.

You need to select the partition(s) the OS is on, indicate the correct format for that partition (what it is now, probably ext4). Most importantly you must choose to not format the drive as this will wipe it clean.

If the current install is on 2 partitions (/ and /home) this is a little easier as you can format the / partition and not the /home partition.

Frankly speaking, assuming you make a full backup of data, I would do a clean install on 2 partitions and transfer the data.

If you are up to the task you could try to rescue the upgrade in a chroot environment from a Live CD live session. You would have to be able to get the chroot to work and if the required files are missing this may not work. You may be able to add the missing files and get it to work.

You would have to make sure that there is a sources.list that is correct.

Run in the chroot environment;
no sudo required at this stage as you are root. And;
If this runs it will probably have errors. Errors or not I would be running;
until you either just get an other prompt as a result or the command or the errors listed are identical to the list before.

Then boot to recovery and run that same command after the tty login.

After that hit "Ctrl+d" and see if that takes you to the normal login screen.

Well There is data on the partition I am worried about, and browsing the partition from a LIVE environment Does indeed shows the files but they are un-copiable, the system says "You do not have proper rights to access these files". To add more trouble There is only one partition , the "/". so I cannot make something like another a new partition. Isn't there any way to repair the previous partition.

You likely need to use admin privileges to get access. Use sudo to prefix a command and get root privileges.
If you have only one partition and want to create another, you can use GParted from the Ubuntu LiveCD. It should be under the System tab on the Desktop. Shrink the partition you currently have and then create another.

Do you want to create another partition to copy data to? or some other reason?
Trying to repair the system, widget explained a method in the above post.