Open the Mac App Store. Hold option and click on purchases. Enter your Apple ID and password used to purchase the App. You will see the iPhoto in the purchased list, Click on install to re-download and install it.
Step 1. Press and hold Command and Option keys and click on the iPhoto icon. Step 2. When a dialog appears with rebuild options, check the options of rebuild iPhoto Library and click “Rebuild” to confirm.
Step 1: If your Photos app is already open, quit the app first and then go to the “Applications” and look for the Photos app icon. Step 2: Once you find it, press Command + Option keys and double click the Photos app icon. Step 3: A “Repair Library” dialogue box will appear. Click on “Repair” to restore your library.
The case of disappearing iPhoto
What happened is that with the very latest OS X upgrade — Yosemite version 10.10. 3 — Apple introduced their new replacement for both iPhoto and Aperture, called simply Photos, like the app already on your iPad or iPhone. If iPhoto was in your dock, it is replaced by the new Photos app.
iPhoto for iOS was discontinued in 2014 and removed from the App Store in favor of Photos.
Back in 2014, Apple announced that they would no longer be supporting iPhoto for Mac, or the company’s professional photography application, Aperture. Instead, a new application called Photos for Mac was launched in 2015.
If your Photos Library won’t open, closes unexpectedly, or throws all kinds of error codes, you can use the Photos Repair Library tool to fix the problem. The tool scans your library’s database and automatically repairs any inconsistencies or corrupted files.
Now, at last, Apple has replaced iPhoto with a new, free Mac app called simply Photos. It’s much faster, less cluttered and has more editing options, yet still makes them simple to use.
If you accidentally deleted your photo or video, it goes to the Recently Deleted folder. Go to Photos > Albums, and tap Recently Deleted in the Utilities section. If you see the missing photo or video, you can move it back into your Recents album.
Photos is the new iPhoto, basically, so your library is transferred over. Aperture users, however, can continue to use Aperture if they want to make more advanced edits. But those edits made in Aperture won’t sync over to Photos and vice versa.