Danny left his laptop on while flying and when he went to open the laptop, the drive disappeared and he doesn't know what happened. Leo says it sounds like the drive had been jostled to the point that the computer couldn't read it. It could still be connected, though. It's likely that the disk catalog was damaged or corrupted. He could run disk utility, but Leo isn't all that confident that it will work for him. Drive Rescue could perhaps fix the problem. Disk Warrior is another.
hard drive recovery
Martinio can't see his external hard drive on his computer when he boots up. What software can he use to fix it? Leo says first he'll have to be able to see the drive to fix it. If he can't see it, then there's a hardware issue. It's a very expensive proposition to get the data off. DriveSavers will be able to do it, but it's very expensive.