Updated my computer to OSX Yosimite 10.10.2, and now my IPhoto wont open

Updated my computer to OSX Yosimite 10.10.2, and now my IPhoto wont open. It said I needed to update to the newest version of IPhoto through the APP store, so I tried, but it has been stuck on 'INSTALLING' for hours. All of my mothers wedding photos, as well as the photos I need for school are in there! HELP!