Missing photo albums I have over 30k photos on my Mac (running macOS High Sierra V10.13.2). They are stored as Events (e.g. Summer 2015), making it very easy to quickly find an individual picture.  I also have an iPad and iPhone 5, both with 64GB memory on which I store all my vital pictures (by selecting certain albums from my Mac when synchronizing). This ensures I have two back up devices.  

However, within the last two weeks all my albums have disappeared from all three devices; all I have are the individual pictures (all 30k of them). Where have my albums disappeared to? There is no way I can recreate each album (even if I remembered all the names) and then copy the relevant pictures into each album - it would take years.  

Can anyone help me recover the albums loaded with the pictures they contained?
Unless you actually backed up your photos, they are, unfortunately gone.


  This ensures I have two back up devices.


This is an incorrect assumption.  What you did was ensure that you had two devices that were selectively synchronized.

There's a major difference between synchronization and backing up.  Synchronization keeps changes consistent across all devices.  This includes deletions.  Backing up makes a copy of the file(s) for safe keeping.

If you delete a photo, file, album, and it's synced with multiple devices, that deletion will propagate across all your devices.  If you had those same files backed up to a USB drive or another service (like DropBox or OneDrive) anything you accidentally deleted would be available for recovery.

As for your albums - they are "containers" that allow you to organize your folders.  If you deleted these containers, the change synched across all your devices.  As inconvenient as this is, consider yourself fortunate that you didn't lose your photos and think of this as a wake up call to implement a proper backup procedure before you inadvertently lose all your photos.