Photo's in iphoto 9 have disappeared

Are you running a "managed' or "referenced" library?

If you're running a managed library try the following:

Make a temporary, backup copy (if you don't already have a backup copy) of the library and apply the two fixes below in order as needed:

Fix #1

Launch iPhoto with the Command+Option keys held down and rebuild the library.

Select the options identified in the screenshot.

Fix #2

Using iPhoto Library Manager to Rebuild Your iPhoto Library

Note: This creates a new library based on the LIbraryData.xml file in the library and will recover Events, Albums, keywords, titles and comments but not books, calendars or slideshows. The original library will be left untouched for further attempts at fixing the problem or in case the rebuilt library is not satisfactory.

OT

So you're running a "managed library", right? Try this: launch iPhoto with the Option key held down and try to create a new, test library. If you can't then first try this: iPhoto_Pref_and_Cache make a temporary, backup copy (if you don't already have a backup copy) of the library and try the following:

1 - delete the iPhoto preference file, com.apple.iPhoto.plist, that resides in your

User/Home()/Library/ Preferences folder.

2 - delete iPhoto's cache file, Cache.db, that is located in your

User/Home()/Library/Caches/com.apple.iPhoto folder.

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3 - launch iPhoto and try again.

NOTE: If you're moved your library from its default location in your Home/Pictures folder you will have to point iPhoto to its new location when you next open iPhoto by holding down the Option key when launching iPhoto. You'll also have to reset the iPhoto's various preferences.

If that doesn't help a reinstall of iPhoto is warranted. To do so you'll have to delete the current application and all files with "iPhoto" in the file name with either a .PKG or .BOM extension that reside in the HD/Library/Receipts folder, reinstall iPhoto from the disk it came on and apply the latest updaters.