Iphoto on my macbook pro has stopped working. It comes up with a message saying that the library is either being used by another user or it is unreadable. Any ideas why I should be receiving this message?

Question

MacBook Pro 2009
Model Identifier: MacBookPro5,1
Processor  2.4 GHz Intel Core 2 Duo
Memory  4 GB 1067 MHz DDR3
Software  OS X 10.8.5 (12F45)
Iphoto '11
Iphoto on my macbook pro has stopped working. It comes up with a message saying that the library is either being used by another user or it is unreadable. Any ideas why I should be receiving this message?
"Your photo library is either in use by another application or has become unreadable"
Offered solution doesn't work:
Shut down and restart your computer, and then open iPhoto again. If the problem persists, try rebuilding your photo library. To do this, quit iPhoto, and then reopen it while keeping the Option and Command keys pressed. You can also try restoring your photo library from a backup.
I have already copied my photographs to the a library manager but when I tried to reuse iphoto and import the photos back into iphoto, it would not let me.
I can't download photographs from my iphone or my digital camera.
Any ideas on how I can solve this problem?
There is a possibility that when I went to update applications that I started to install Mavericks which I then interrupted and cancelled. I am not definite that this caused this problem but it was at about the same time as when this problem started.
Many thanks,
Ed

Answer 1

I have already copied my photographs to the a library manager but when I tried to reuse iphoto and import the photos back into iphoto, it would not let me.
You can't "copy" your photos to the "library manager", there is just no way to any such thing.
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