IPhoto library on external hard drive will no longer open

Question

I'm hoping that someone will be able to point me to a simple solution to my problem...
I'm running iPhoto 9.6 on a  MacBook Pro (Retina, 13 inch, mid-2014).  The OS is Yosemite 10.10.1.  Because the flash storage is only 250GB I have my main iPhoto library (146GB) on a partition of an external 1TB Lacie Rugged drive.  The external hard drive also has partitions for Time Machine Backup and SuperDuper Bootable Clone.  I have a separate, much smaller iPhoto library on the MBP which contains recent photos.
Yesterday I failed to reconnect my MacBook Pro to the power source when I put it back on my desk.  The result was that the battery went below 5% and the MBP turned itself off and also ejected the external hard drive (some time after I reconnected the power cable there were dialog boxes on my screen informing me that each of the three partitions had been ejected incorrectly).  I waited until the MBP was fully charged before I tried to open my 'main' iPhoto library on the external hard drive.  I received a message that the library would have to be upgraded to work with the computer (very odd, because it had already been upgraded last October when I upgraded from Mavericks to Yosemite and has been working without any real problem ever since then).
After some hours when the only message on the screen was 'Rebuiding Thumbnail Caches' I pressed Cmd+Option+Esc I saw that iPhoto was 'Paused'  - that message subsequently changed to 'Not Responding'.  I 'Force Quit' iPhoto but the iPhoto library will not open at all from the external drive.
As a test I quit iPhoto and re-started using the Option key and chose to open the iPhoto library which is on the internal drive and it opened without any problem.
I recall that it used to be possible to fix this sort of thing (perhaps not) by trashing the com.apple.iPhoto.plist file, however, I don't seem to be able to find it :-(
I'm really at a loss as to how I should approach this problem and I would be very grateful for any suggestions that can be offered.
Cheers
Tricia

Answer 1

Further update ....
I downloaded and installed iPhoto Library Manager and then chose Library - Rebuild Library.  Unfortunately, when it had finished the result was 0 images in any file or folder.  I checked the log (which is incredibly long) but here's the beginning of it which seems to indicate that the problem is that an essential file is missing -
2015-01-21 10:49:18.671 iPhoto Library Manager 4.1.11; iPhoto 9.6; OS X 10.10.1; unregistered
2015-01-21 10:49:19.033 Rebuilding library /Volumes/Pictures/iPhoto Library
2015-01-21 10:49:19.033 Rebuilt library located at /Users/Tricia 1/Pictures/iPhoto Library (rebuilt).photolibrary
2015-01-21 10:49:19.035 Building preview…
2015-01-21 10:49:19.042 Photo transfer settings: source libraries = /Volumes/Pictures/iPhoto Library, copy faces = true, copy places = true, combine album contents = false, photo attributes copied = (comment, date, flagged, hidden, latitude, longitude, name, rating)
2015-01-21 10:49:19.042 Loading data for library /Volumes/Pictures/iPhoto Library…
2015-01-21 10:49:19.056 Version number: 9.6
2015-01-21 10:49:19.057 An error occurred: Trying to load database for library “/Volumes/Pictures/iPhoto Library” failed. Some information such as faces, places, and edit history may not be transferred succesfully. (error = Error Domain=PLDatabaseErrorDomain Code=1 "The SQLite database file could not be found." UserInfo=0x10e9c1c10 {PLDatabaseErrorVendorErrorKey=14, PLDatabaseErrorVendorStringKey=unable to open database file, NSLocalizedDescription=The SQLite database file could not be found.}
After this each entry has a dialog that basically says the image file is missing from /Volumes/Pictures/iPhoto Library.
As mentioned in an earlier post I do have another iPhoto Library on my 2008 MacBook.
Can someone advise the best way to proceed?  I'm thinking that I should erase the partition of my external hard drive that is called Pictures and then connect the external hard drive to my 2008 MacBook and simply drag and drop the iPhoto Library to the Pictures partition.  IIRC, that's the way I moved the iPhoto Library last October when I bought my new MacBook Pro which didn't have enough storage for me to be able to store my iPhoto Library on the MBP.  I could then reconnect the external hard drive to my MBP and the iPhoto Library should reappear, shouldn't it?
Looking forward to more input ...
Tricia