Well, if the Original Poster is a little technical minded, she's got some more things to try, to avoid the warranty process (considering the time it sometimes take):
- Some laptops have built-in recovery. It can be initiated by pressing a button (usually one of the function buttons, consult your manual). Of course it relies on a working hard drive with the recovery image on its hidden partition. And if successful, it erases all user data, so backup is still necessary if important files are there. But if it works, we get to know a couple things:
a) the hard drive is in working condition,
b) the partition table is intact
c) the failure to boot was caused by something (still can be either hardware or software problem) that prevented the operating system to load.
If it's successful, and the restored system boots, a disk check is still due, to be sure that there are no bad sectors.
- Other thing to try: create a bootable Ubuntu CD (maybe on a pendrive), and boot on it. If the system partition on the hard drive is there, and the file system exists, then it will be possible to copy files over another pendrive or external hard drive, or to another computer through network/internet.