I am not an IT tech but have changed hard drives and I see no way a hard drive gets a scratch. If someone could explain how it would be appreciate. What I think is happening is that they discovered that the HD was shredded like they thought so them made an excuse. OR for a bigger conspiracy theory it is not her hard drive at all it is one they made to appear to be hers, it just took this long to do so. What is on the HD will tell the story.
It shows you are no tech expert.
Hard drives are like record players. They have "heads" or something that functions like a "needle" that "seeks" or finds data. If you listen to the computer you can actually hear the parts moving when you perform a "seek" functions.
Eventually they do fail and the disks can become scratched.
A sector can become scratched, but it is, most times, only a small amount of data affected. And even it can sometimes be recoverable. Think of a record player. You know how the needle can scratch a record if bumped severely or by happenstance by mis handling of the record off the player? Well, you can still play the record, it might hang at the scratch, but you can move that needle to get it to continue to play. Obviously, within an enclosed hard drive, you can't mishandle the disc physically, unless maybe throwing the drive or laptop across a room into a wall, etc. while it is working. Do things happen sometimes with age? Yes. But most all data can still be recovered when you fix the head or remove the disc to another apparatus. Could a minute amount of data have been lost? Yes, but most all is recoverable, just as you can continue to hear most of that record even it has become scratched. For those not familiar with records and record players, even a scratched record can most times be restored.