Re: Lucid no longer boots / Can boot from CD or flash card either.
No, this does not sound like grub. USB/CD boot (attempts) come before grub (on HD) is started; as the former already fail, it's not a grub issue. And you can boot windows which implies that at least the grub files in the Linux partition are still fine (if you're using grub as the boot loader).
I would try to 'reset the bios' as a possible solution.
If you don't make backups of your important data, your data is obviously not important to you.