l. I only have or had one (1) album of photos.
Do you mean by "album of photos" your iPhoto library or that you now are seeing only one album in your library?
Have you checked the obvious places for missing photos - looked into iPhoto's Trash, checked if Hidden Photos" are disabled in the "View" menu?
If your library is not showing all albums that should be there, try if repairing or rebuilding your iPhoto library will turn the photos up again, see Old Toad's post on how to do this:
If all this does not help, then tell us please, what happened before your photos vanished.
- Did iPhoto crash?
- Did you update software or install new software, that you used for the first time?
- Did you move your iPhoto library somewhere else? To a new drive or cloud storage?
- Did you import new photos?
- Did you delete any photos that were apparently not in iPhoto? For example with a cleaing and space-saving application. like Clean My Mac?