When you need to find everything you haven’t flagged, here’s two ways of doing it
The long way (using the menus) is to:
1. First click on the Folder containing the photos to check
2. In the Library module, choose Library > Enable Filters (if it is already checked then don’t select it!)
3. Choose Library > Filter by Flag > Unflagged Photos Only to see the unflagged photos.
If you flag any photos with this filter in place, they will immediately disappear from view – because they are no longer umflagged – they won’t match the current filter.
When you are done, click Filters Off to go back to viewing all the photos.
The second way to isolate unflagged photos:
Again, is to click on the Folder containing the photos to check
Now, on the Filter bar, just above the Filmstrip click the middle of the three flag icons. You will see the Unflagged Photos alert appear temporarily to indicate you have selected to view unflagged photos only.
When you are done, click Filters Off.