Hard drive suddenly appears unformatted--possible to recover?

Heh. I actually have done that before. Why would or do external drives often cost less than internal drives, when they seem to be the same hardware with extra stuff like an enclosure and a SATA bridge (that is the right term for that card that connects from the USB and power source to the drive’s SATA and power connector, right?) The price difference wasn’t always that much: maybe 10 or 20 bucks. So it appears you can’t do this with all external drives anymore from what you’re saying, right?

I’ve had success reviving cactus drives with GetDataBack

It seems to be a marketing thing.

Correct

I have also had good luck with Spinrite