Yosemite iPhoto Problem

Question

Hello,
I upgraded to Yosemite about a week ago, ran the upgrader package and for the first few days iPhoto worked just fine.  Then a few days ago, when I opened iPhoto, none of my pictures were visible.  I have my iPhoto library on an external HD and the file size is still 115GB, so I know the images are still there.  I tried to go to an earlier version of iPhoto in my time machine thinking that may solve the problem, but no luck.  I'm hoping somebody might have had a similar experience and might be able to help.  Thanks in advance
Set Up:
MacBook Pro (13-inch, Mid 2009)
Running Yosemite 10.10.2
iPhoto 9.6.1

Answer 1

What format is the external?
Option 1
Back Up and try rebuild the library: hold down the command and option (or alt) keys while launching iPhoto. Use the resulting dialogue to rebuild. Choose to Repair Database. If that doesn't help, then try again, this time using Rebuild Database.
If that fails:
Option 2
Download iPhoto Library Manager and use its rebuild function. (In early versions of Library Manager it's the File -> Rebuild command. In later versions it's under the Library menu.)
This will create an entirely new library. It will then copy (or try to) your photos and all the associated metadata and versions to this new Library, and arrange it as close as it can to what you had in the damaged Library. It does this based on information it finds in the iPhoto sharing mechanism - but that means that things not shared won't be there, so no slideshows, books or calendars, for instance - but it should get all your events, albums and keywords, faces and places back.
Because this process creates an entirely new library and leaves your old one untouched, it is non-destructive, and if you're not happy with the results you can simply return to your old one.  
Regards
TD