all thumbnails are gone

Download iPhoto Library Manager and use its rebuild function. This will create a new library based on data in the albumdata.xml file. Not everything will be brought over - no slideshows, books or calendars, for instance - but it should get all your albums and keywords 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.

I had the same problem. I downloaded library manager. Now I can't find where my original library went. I only have the new file with nothing in it. I have over 20,000 pictures in my original IPhoto.

IPhoto said I need to repair my program and when it was done I had no thumbnails and most of the pictures were rotated funny. I am currently rebuilding my library through library manager. 2 questions I'm only partly through but everything is coming up as untitled events??? Also will this program permnantly change the name of the photos? In the past when I try to send pictures to someone it reverts back to the file # name. I am working a lot of family pictures that I need to share but I need to have the "who, when and where" as the name of the picture. How can I do this? Thank you

I wonder if you have got to the bottome of this yet. I have had a nightmare, and today i am ecstatic that i have found the solution. Many of my thumbnails were grey after I reinstalled from Time Machine, and after very much time I discovered that it was only the edited photos which were affected, so I started exporting those photos individually and then importing again, but I refined this by duplicating the greyed out thumbnail in iPhoto, then deleting the grey one, and it is restored edited and all. Brilliant. Can even do a bunch at a time, like 'command' 4 or 5 probably more at once. Hope this helped and not too late