Rule Out the Connection
Diagnostic
Rule out the port before the drive
A dead port and a dead drive look identical from here. Ten minutes tells them apart, and it is the difference between wiping a stick and throwing away one that was never broken.
If the computer offers to format or initialise the drive while you work through these, say no. On a Mac that means leaving "Initialize…" alone: it opens Disk Utility, one step from erasing what is still on there. Nothing gets wiped by accident on this route. If it happens at all, it is a decision you make later, with the alternatives already ruled out.
- Plug it direct into the computer. No hub, no dock, no keyboard port, no extension cable.
- Work through the other ports, the ones at the back included. Front-panel and keyboard ports often cannot feed a drive enough power to mount it.
- If the drive uses a cable, swap it for one you know carries data. Plenty of them only carry power, and they look identical.
- Then a different computer, a different make if you can get to one. That is what separates a dead drive from one machine that will not mount it.
After all of that, do the files show up?
You follow these steps at your own risk. Full disclaimer.