i tried the ubuntu page https://help.ubuntu.com/community/IntrepidUpgrades
but it was of no help. the command it told me to run did n't worked. the complete method was according to that page was :
Use this method if the system being upgraded is not connected to the Internet.
Download the alternate installation CD
Burn the ISO to a CD and insert it into the CD-ROM drive of the computer to be upgraded.
If the ISO file is on the computer to be upgraded, you could avoid wasting a CD by mounting the ISO as a drive with a command like:
sudo mount -o loop ~/Desktop/ubuntu-8.10-alternate-i386.iso /media/cdrom0
3. A dialog will be displayed offering you the opportunity to upgrade using that CD.
4. Follow the on-screen instructions.
If the upgrade dialog is not displayed for any reason, you may also run the following command using Alt+F2:
gksu "sh /cdrom/cdromupgrade"
Or in Kubuntu run the following command using Alt+F2:
kdesudo "sh /cdrom/cdromupgrade"
But thoose commands just did not worked. help me out.