Q: Photo Folders & albums missing

Did you migrate an Aperture Library or iPhoto Library to Photos?  Photos does not support iPhoto Events or Aperture projects.

When you migrate a library,  all your iPhoto events or Aperture Projects will be represented by albums, and these albums are collected in a folder "iPhoto events".  Is this folder missing?  See:  How Photos handles content and metadata from iPhoto and Aperture - Apple Support

If albums are missing, check, if these albums have been smart albums.  Photos does not support all contraints, so some smart albums may be missing too.

Folders and albums should only vanish, when you delete them.  But some users here have reported a bug, that their albums were suddenly deleted after they enabled iCloud Photo Library on an iPad. Syncing the libraries removed the albums  Did you recently enable iCloud Photo Library on an iPhone or iPad?

If that should be the case, there is no known fix other than restoring the library from a backup to recreate the albums.  It might be quicker to recreate them manually, because uploading the library again to iCloud will probably take much longer.

There is no separate backup of iCloud Photo Library.  Apple's device backups don't include items that are already in iCloud (see:  iCloud: Backup and restore overview).

You need to backup your Photos Library separately.  The easiest way would be to include it in your regular Time Machine backup.  See this Help page for Photos:                Back up your Photos library      

I have not used that software in incremental mode, so I do not know how you can restore an older backup from a carbon copy clone. You'll have to look at the manufacturer's website.