Ubuntu PArtition Lost

[ziaur25]

Hello,
I have been in a Big Trouble.
I have been working Ubuntu Gusty Gibbon and
Windows XP OSs.
I used Ext2IFS software to view Ext partition
in Windows. Then Accidently I deleted that Linux
partition thro windows Disk Management Program.
Then I recovered the Entire deleted partition
thro Partition Table Doctor(No data is lost).
But still i cannot able to use that ext partion
as linux root. When I used Ubuntu live CD, fstab
command displays that ext partition. But does not
takes as root partition. Even i am unable to access
thro' the 'su -' command, when I type the password
it displays 'Authentication Failure'.
How can i restore my linux partion as /(root).
I need ur help....
my mail id ziaur25@gmail.com

Thanksss.

[Intrepid Ibex]

fstab command displays that ext partition

you mean 'fdisk'?

Also setting root password can be done by:
sudo passwd

You could also just use sudo or:
sudo -s