tried to run mount -o remount,rw /dev/sda
but issue is not resolved
please suggest

you can create file /etc/fstab and then put like below

Noh, you were trying to edit the running fstab locked by the liveCD, of course that's a big "no" as a rule.

The running system locked it.

Yes but the liveCD system is greater than you.

-----x

Your problem is simple, you only need to reconstitute a text file and put it into its proper place. Had you posted to us your 'fdisk -l' output we would have known enough what file system you run, an ext2, ext3, ext4 or raiser? and would have posted you the correct texts. Run --# fdisk -l first and find ascertain the partitions and edit the instructions below accordingly.

Here is what you need to do.

1. Boot the live CD.
2. Check the partition: root@livecd-# fsck -a /dev/sda3
3. Mount it rw:
root@livecd-# mkdir /mnt/mysda3
root@livecd-# mount -o rw /dev/sda3 /mnt/mysda3
(Now it's there waiting to get manipulated.)
4. Follow these series of terminal commands:
--# touch fstab
--# echo '/dev/sda3 / ext3 defaults 1 1' >> fstab
--# echo 'proc /proc procfs defaults 0 0' >> fstab
--# echo 'tmpfs /dev/shm tmpfs defaults 0 0' >> fstab
--# echo 'devpts /dev/pts devpts user,rw 0 0' >> fstab
--# echo '/dev/cdrom /media/cdrom iso9660 noauto,user,ro 0 0' >> fstab
--# chmod 766 fstab
--# cp ./fstab /mnt/mysda3/etc
(Take note of the spaces and single quotes (') and the pipe >>)
(Assuming that your /, /boot and /tmp dirs reside in the same partition, it's a go)
Now it's time to reboot into your hard drive root.

After logging back into the old system you must recover the original fstab from the trash and replace the one you temporarily made.

Hope this helps. Good luck.

@miteshpant

You can mark your thread as solved using the threadtools just above the first post on a page

PS You already double posted the solution in 2009 So how can one miss it