If you are lucky, this is just an Xserver problem, so you can try booting into the recovery mode kernel and running
That will reset xorg.conf to a default detection. Hopefully now you can get back into Ubuntu.
If that fails, you may need to boot from the LiveCD, mount your internal hard drive with your data, then mount a USB hard drive and copy your data from the internal to your external drive as a backup. After you are sure you have everything, you can reinstall (a fresh install of Hardy) and reload your data onto the machine.