LR 15.1.1. Mac running Tahoe 26.2. LR has lost 1285 photos,

Have you tried using Spotlight (Apple Find feature) to search for those photos? Lightroom doesn’t just delete files so they are likely on a drive somewhere.

Hi, ​@nickthereef, I am assuming that you are referring to LRC (Lightroom Classic), not LR.

I can think of two possible ways the images “disappeared.”

1) Where are the files located? On your computer or on an external hard drive? If so, did you unplug the external hard drive? If you’re on a Mac, have you given the OS permission to access external hard drives? (If you need more information on that let me know.)

2 If you’ve moved files around in the Finder or Explorer, LRC doesn’t have a clue as to where they are located. LRC is focused around a database. Anything you do INSIDE LRC is known by the database. Anything done OUTSIDE of LRC is completely unknown to LRC. So, for example. If you have a folder called “My clients,” and in the Finder/Explorer, you rename it to “My Favorite Clients,” LRC doesn’t have a clue where the files are because you changed the name of the folder. Similarly, if you moved a number of folders into another folder in the Finder/Explorer, or created new folders to put them into, the same issue will happen. [Note: do not ask me how many times I’ve done this before I stopped doing things like this.]

Quick example: Your name on these boards is “nickthereef.” If you decide to change your name to “dimethereef,” you can’t get into these forums because you changed your name outside of Adobe’s knowledge. It’s no different here.

If you see exclamation points “!” inside the thumbnails, that’s a clear indication that either #1 or #2 has occurred. To remedy this, click on the “!” and it will ask you where the file is located. Then, using the Finder/Explorer, dig into your system, locate that one image, and all of the images in that one folder (including sub-folders) will become available. If there are images in other folders that have been renamed or moved, you will have to do them separately.

Any time you rename or move folders around, or from one hard drive to another, all that must be done inside LRC from now on. 

I hope this helps you.

Regardless of whether you deleted them or not, the photo files are still on your computer or external disk(s) wherever they were, all you have to do is search for them. Unless you accidentally deleted them … which does happen sometimes.

Please specify ‘lost photos’. Are these photos not in the catalog anymore, or are they in the catalog but shown as ‘missing’? If the latter, is their folder shown as missing in the folder panel (name in italics and question mark in front of it)?