Q: I can't open iPhoto

Apple must have discontinued iPhoto as it no longer is available on IOS or Mac sorry There is a few apps on the app store that are now a successor to the iPhoto app take a look

The only iPhoto version working with El Capitan is iPhoto 9.6.1.  Dod you already update to this version?

The iPhoto icon will be missing from the Dock, but open the Applications folder and drag the iPhoto icon back to the Dock.

If the iPhoto icon looks crossed out, your iPhoto version is incompatible. Not all iPhoto versions can be updated any longer.

iPhoto has been discontinued by Apple and is no longer sold at the AppStore.  The Updates tab of the AppStore does no longer work for iPhoto at all.

You can only update iPhoto by reinstalling from your Purchases history.  Does iPhoto show for you on the fourth tab "Purchased" at the AppStore? If not, try to unhide it: Hide and unhide purchases in the Mac App Store - Apple Support

Then follow the instructions in Barney's user Tip:    Can't Update iPhoto because it is not available in the App Store

hi everybody, since my last update I can not use iPhotos, i don't know what happen, i am working with OS X EL CAPITÁN, if anyone can help me will be fabulous.

if you already updated to iPhoto, but it cannot open your iPhoto Library, post back with  ore information on what happens, when you try to open iPhoto.

If you cannot update to iPhoto 9.6.1, because your version of iPhoto is not an AppStore version, open your iPhoto Library in Photos for MAc.

Photos for Mac should be in the Dock with a rainbow colored flower icon. Drag your iPhoto Library onto this icon and Photos will migrate it.

How Photos handles content and metadata from iPhoto and Aperture - Apple Support

In that case make yourself familiar with Photos for MAc.  It can open your iPhoto Library, the editing tools are even better than in iPhoto, and only the structor of the Photos library needs bit of getting accustomed to.

The online help for Photos is here:  Photos Help