I was using ubuntu as my OS.But when upgrading to version 9.1 the trouble started.Ubuntu has not been fully and correctly installed. So it does not work. How to make my ubuntu work properly?Is there any CD to correct ther mistake? If there is a CD where and how to get it?

What's not right about the installation? Will it not boot?

Assuming it will not boot, the likely suspects are mounting of the / filesystem or the bootloader. Help us out and give some symptoms. What do you see on the screen? Any messages you could share?

If you upgraded instead of a fresh installation, a frequent problem is that the partitions will be named differently and /etc/fstab will need to be edited. You can use the installation CD as a rescued CD to do that or you could use SystemRescueCD. Mount the file system. Identify the drives with blkid or look at /dev/disk/by-uuid/ and cat /proc/partitions. Enter the UUID= in place /dev/sdxy in /etc/fstab, save and reboot.

editor /etc/fstab

It should look something like this:

UUID=a2d22199-ea79-49ef-8b2e-a43e360965cf        /               jfs     errors=remount-ro 0       1

I have jfs file system. Keep yours as it is.