Simple question. My HDD is recognized by my disk utility, but it refuses to mount. Can I assume it is dead?

Might not be a simple answer. Could be just partition issues, could be firmware issues. Without further info I can speculate on anything that could be causing the failure.

Is this a mac ( based on the fact you said Disk Utility)?

What kind of drive is it? ( Make/Model)

Can you show us a screen shot of your disk utility.

There might be a good chance it can be recovered.

We will try and help if we can.

It's an old Seagate Barracuda 500GB disk. I've pulled it, so I don't have access to the Disk Utility screen shot. Yes,it's Mac Monterey.
It's been working fine for several years, but suddenly refuses to mount. If if won't mount, there isn't much one can do to fix it, is there? That is, partitioning and firmware update are sort of off the table.

Still could be anything that could be wrong with it. But it is quite possible it could be recoverable

If you have another working computer you could try and get a usb to sata adapter and see if it recognizes on that computer. in disk utility on mac or disk manager on a pc You can also see if it is making any weird noises.

I see you are in Texas, I am in Austin and can take a look at it if you would like. If not you could try a local tech shop and have them to a preliminary check and if it is a simple fix they may be able to get your data.

Can you show us the Partitions tab in DMDE?

Can you show us a SMART report, ie the SMART attributes?

_________________
A backup a day keeps DR away.

Well, thanks very much. Not sure it's worth it, though. This is a ten-ish year old unit, and I'm trying to upgrade to SSDs anyway. I was mainly curious about what could allow a disk to be recognized by Disk Utility, but not be mountable. As in, I know you're there, but I can't mount you.

I think it's a 7200.12, though that isn't very conspicuous. The STX is 720012. Certainly no SMART capability. Again, this drive worked for many years. There were no obvious changes. It suddenly just decided that it didn't want to mount.