Move Ventura OS Back To Hard Drive - iMac

Something is just not right. If you didn't erase the internal drive, the OS is still there. It may be damaged, but unless you actively erased it it's still there. That notwithstanding.

You can do this: Create a bootable installer for macOS - Apple Support. But this will totally erase your drive.

Or you can attempt to reinstall the OS: How to reinstall macOS - Apple Support. Choose the "Reinstall the OS from Recovery" option; I'm assuming from your info above you have an intel CPU machine. When you restart and use Command + R, you have to be quick about it or you'll miss the window of opportunity. I suggest you try this first. You may need to try it several times. You may also need to hook your rechargeable keyboard up to the Mac to have it emulate a wired KB.

Needless to say, be absolutely sure you backup ALL your important data on ALL drives before you attempt anything.

Just a comment. Having a bootable external drive can be the solution to a slow iMac. But moving the OS simply because you need more space is not a prudent solution. At best that will get you maybe 18-20GB or so, the OS footprint, whereas you need hundreds of GBs most likely doing the work you do. You can add external storage just by attaching a drive.

You're going to be better served by not migrating 3rd party apps; reinstall them. If they are licensed, that may well present a problem and that you'll have to work out with the developer.

Data can be moved in various ways. In your case I suggest the simply way ... copy it back using Finder. But if you were experiencing disk space issues, you'll be right back where you started and still need additional storage and that's going to mean an external drive. And it too should be backed up.

"The Mac hasn't been tampered with but it thinks there is no internal hard drive. " So I assume you are the one who moved the OS.

It's your Mac so I'll go with that, but again, something is not right in the usual sense.

My next thought is the internal drive has suffered a catastrophic failure. If you can't see it in Disk Utility, can't boot from it and can't select it as the startup drive I'd assume it's damaged beyond recognition much less repair.

If you wish to attempt to salvage the disk, I suggest you get it to Apple for an evaluation. But depending on the age of the Mac, you might be in a situation whereby the cost to repair, if they agree to repair it, may be greater than the value of the Mac. You've yet to say how the Mac is.

If the internal disk is dead, you've already solved that problem with an external boot drive. Leave it alone and continue to start up from it. That is a very acceptable solution.

"Unfortunately, Adobe Lightroom doesn't work with this new setup, and I've tried everything" This should not be happening. Adobe doesn't care what disk it runs from as long as there's sufficient disk space, enough RAM and it's properly licensed if that's required.

Since you appear to be limited to the external boot drive, I suggest go with it still and contact Adobe for tech support. They do not need to know what drive the app is running from to help. Well, we haven't used Adobe in a very long time so for all I know they may have made a genius move to that effect. But I doubt that, they want the business too badly.

All this is just my solution and comments. Believe me this community is filled with members far more knowledgable than I am, so I'll just stop here, I've said all I can and there's no need to repeat myself, and let others take a crack at helping you.

So what you did was create a bootable external macOS drive? Is that correct? " moved the OS, applications and all other items to a 1TB Lacie SSD"

If you did so but didn't erase your internal drive, the OS is still on it. Did you erase the internal drive?

If you did not erase the internal drive, it's just a matter of selecting the internal drive as your boot drive. But you need to confirm exactly what the status is of the internal drive first before moving forward.

There are a couple of ways to select the internal drive; both rather simple. System Settings > General > Startup Disk. Choose the silver Macintosh HD drive.

Actually you can try that now. If the disk is there, select it and you're home free. If not, you'll need to reinstall the OS onto the internal drive.

Once this is settled, we can deal with storage issues. But you need to get the drive thing sorted first.

What drives, by name, do you see when you do System Settings> General>Startup Disk? Your disk may not be named Macintosh HD.

You probably don't see the internal drive because it isn't selected for viewing under Finder. Open Finder and click on the apple logo in the top left then go to setting and general. You should have all the boxes check for internal and external drives. You should check any of the rest that you may need to see. If the Mac boots and the images of your wife's are still there, then your MacOS and boot drive is good. You need a big SSD to "move" all of those images off the boot drive... aka backup. If you're attempting to replace the boot drive, you need a disk image created for it. Disk Utility will be able to do that. You will need enough space to make the image on a drive. Then you will need your new drive connected. Restore the image from the Disk Utility to your new hard drive. That way your original drive is still there; the wife's image are on another drive and they won't take time in the image creation; your new drive will boot once you have removed the original drive.

Maybe this isn't the direction you have taken... but I would stop the press and make sure you have a good readable backup of your wife's images! Get a usb stick and backup those first. Then you can do anything you want with images and restore of images to the iMac.

Restart and look again

But if the OS is gone, somebody removed it. Is this a used computer? Who did the OS moving? My guess is work was done and you were newer told was all was done.

An OS does not just suddenly disappear off a working drive. Somebody, a current or past user or a third party, removed it somehow. Are you sure the disk is actually still in the Mac?

At any rate, you now have links that tell you exactly how to install the OS. If you go that route, follow the instructions precisely and do not skip any steps that apply to your Mac.

Good luck

EDIT; "to say how old the Mac is".