Sure, unless your disk is garbled or you have reformatted it entirely...

Just mount manually your hard disk partition:

to find out wich one it is try: cat /proc/partitions

This will show your disks partitions. If your hard drive is on /dev/sda, try
(as root) : gparted -l /dev/sda
It will list your partitions.

Then, you can mount them and backup/change whatever you need.

example: # mount /dev/sda1 /media/boot

May be you will have to reinstall grub if it's messed up.

See this: http://ubuntuforums.org/showthread.php?t=24113

Don't despair. Chances are your data is still intact.

Do someone knows for sure, but I think Ubuntu 2010.04 comes with the new Grub2.
May be this is a to the source of your problems...