I tried: apt-get install grub-pc /dev/sda
and: sudo apt-get install grub-pc /dev/sda
but got error messages.
Next: sudo mount /dev/sda6 /mnt
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
sudo chroot /mnt
sudo grub-install /dev/sda
worked but it got hung up on one of the commands so I killed the operation, however, after reboot linux automatically opened up. I also can boot into xp.
btw - in response to syg00: I did do the sudo update-grub after reboot yesterday.
Thank you all very much.