First of all, Leo says to not mess with the hard drive any more because it could make things even more difficult. It's time for the experts. In most cases, it isn't a physical problem, but a software issue. There may be bad sectors and the drive isn't able to boot up any longer. If this is the case, it won't be near as expensive and may be recoverable with a program like SpinRite. If it is a physical problem though, like a dead circuit or a crashed head on the drive, then Danielle should take it to Drive Savers. In either case, it really should be left up to a professional at this point.
Danielle did notice that some of her photos were showing up on her AppleTV in screensaver mode. Leo says that means the images are backed up via iCloud or MobileMe. If they're still on MobileMe, she should get those before the end of the month when MobileMe shuts down.