I did that to save space.
Now I see GRUB loading, please wait ... ERROR 15
/boot still has files corresponding to 2.6.32-27 version of Linux. But I deleted all others that did not have that string in /boot
What can I do ?
First the lecture:
Rule Number Zero: If you do not understand what something does, DO NOT TOUCH IT
Deleting files "to save space" with no concept of what you are doing will anger the operating system gods, resulting problems similar to what you are now experiencing (Things break. Fixing them is often non-trivial).
Now the sympathetic assistance:
Fortunately you have not destroyed the universe: Fixing this particular problem is relatively trivial. Locate an appropriate boot CD (your Ubuntu install disk should be usable as a LiveCD) and run
grub-install with appropriate parameters to re-install the files
grub is looking for in your
/boot directory (you may want to google around for further information).
You will also need to
dpkg-reconfigure grub to rebuild the grub menu and various other bits and pieces you may have blown away.
I have intentionally left this answer somewhat vague, pointing you in the right direction rather than giving you line-by-line commands - you can get all the gory details of what to type and why from the internet.
A little legwork is often good for the soul, and will increase your understanding of the Linux boot process...