Q: iPhoto will not open

As a Test:

Hold down the option (or alt) key and launch iPhoto. From the resulting menu select 'Create Library'

Import a few pics into this new, blank library. Is the Problem repeated there?

Post back with the result.

You need to tell us exactly what version of iPhoto you have. You can ascertain this simply by selecting the App in the Applications Folder and going File -> Get Info

Try trash the com.apple.iPhoto.plist file from the HD/Users/ Your Name / library / preferences folder.

(On 10.7 or later: Hold the option (or alt) key while clicking on the Go menu in Finder to access the User Library)

(Remember you'll need to reset your User options afterwards. These include minor settings like the window colour and so on. Note: If you've moved your library you'll need to point iPhoto at it again.)

What's the plist file?

For new users: Every application on your Mac has an accompanying plist file. It records certain User choices. For instance, in your favourite Word Processor it remembers your choice of Default Font, on your Web Browser is remembers things like your choice of Home Page. It even recalls what windows you had open last if your app allows you to pick up from where you left off last. The iPhoto plist file remembers things like the location of the Library, your choice of background colour, whether you are running a Referenced or Managed Library, what preferences you have for autosplitting events and so on. Trashing the plist file forces the app to generate a new one on the next launch, and this restores things to the Factory Defaults. Hence, if you've changed any of these things you'll need to reset them. If you haven't, then no bother. Trashing the plist file is Mac troubleshooting 101.

Switch to another user account and repeat the test there.

My 2012 thru present are not there. Did something happen in late 2011 that changed the way IPhoto stores data?

No.

Ok. I looked in the other users and could not find the apple.plist files. Is that because I deleted it while in my user?

No.

Given that iPhoto opens normally in the other user account we can surmise that the app is fine and the issue is something in your main user account.

I asked you above:

As a Test:

 

Hold down the option (or alt) key and launch iPhoto. From the resulting menu select 'Create Library'

You answered:

I have tried holding the control and command keys then opening IPhoto.

Which is different from what I asked you to do. Can you try the test to create a new library?

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

I would guess that you might have more than one Library on there.

Hold down the option (or alt) key key and launch iPhoto. How many libraries are listed?