Why did my photos disappear in Photos App?

I also noticed that at the same time all my Desktop photos and folders with photos went away . I must t have done something wrong, but don''t know what

Sounds like you logged into a different account on that Mac.

Maybe your Photos Library got swept into another folder as you were moving the cursor around, and Photos can't find it. Use Search in Finder to hunt for your library-- they have the extension ".photoslibrary" so you can search for that.

If you find it (the first library that Photos creates is named "Photos Library.photoslibrary") then select it and you can find the path at the bottom of the window. Photos libraries are usually kept in the Pictures folder, but you can see above that one of mine snuck into the Documents folder. You can drag an errant library back to Pictures and double click on it to open it in Photos.

How can we possibly know if you don't explain the relationship you have created between Adobe Lightroom and Photos? You have to explain that because this is not something that is built-in and in fact, it's quite arguable that using two apps for the same job makes little sense. Be sure to include the variant of Lightroom you're using too.

There is no relationship between LR and Photos. So, unless you created one, moving your Lightroom collection is not what caused your issue with Photos.

So what do you see when you open Photos? An empty window? Are you sure you don't have more than one Library?

Again, given that LR and Photos do the same job, but LR is more capable and you're paying for it, why use Photos at all?

donmcd wrote: two empty Photos Apps. How, do I move them back to the desktop App?

I am guessing you mean two empty Libraries. If they are empty, you can delete them.

And Libraries are not usually kept in the Desktop folder-- they are usually kept in the Pictures folder. They can be anywhere, but Pictures is the default folder.