Remember: we cannot see your machine. There are 9 different versions of iPhoto and they run on 8 different versions of the Operating System. The tricks and tips for dealing with issues vary depending on the version of iPhoto and the version of the OS. So to get help you need to give as much information as you can. Basic things like :
- What version of iPhoto.
- What version of the Operating System.
- Details. As full a description of the problem as you can. For instance: 'iPhoto won't export' is best explained by describing how you are trying to export, and so on.
- History: Is this going on long? Has anything been installed or deleted?
- Are there error messages?
- What steps have you tried already to solve the issue.
- Anything unusual about your set up? Or how you use iPhoto?
Anything else you can think of that might help someone understand the problem you have.
Posts that consist of "iPhoto doesn't work. Help" or "iPhoto won't print" or "Suddenly I have no photos!!!!!!!!!!" mean that any helper is simply guessing. More information means you get better assistance.
Download iPhoto Library Manager and use its rebuild function. (In Library Manager it's the FIle -> Rebuild command)
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.