Who knows, but i recently had my backup drive bay corrupt both backup drives...and windows not able to read them even when put into a new external bay. Windows showing not initiased and no partitions...
I used test disk and it was able to fix them both..without having to recover any data.
If all that's wrong is partition table or boot sector then you can repair. Using Testdisk or another tool (DMDE is easier to use IMO). But in general, an unwritten rule in data recovery is not to write to the 'patient'. So in case I make in-place repairs, I first create a sector by sector disk image.
Risk is that people who don't have a clue about what's wrong with the drive at random start running all kind of repair tools such as Testdisk. Since I can not tell in advance how computer literate a person is, how well he understands disk structures, without having any background info about the actual case at hand, I'll never suggest Testdisk.
It's not uncommon for RAW file system, or Unallocated type situations, which in themselves are signals for a logical problem, have an underlying physical cause.