downloaded Iphoto upgrader - lost iphoto albums/photos

Hi everyone,

I updated my Macbook Pro (2013 version) to Os X El Capitan (version 10.11.4). When I tried to open iPhoto (9.6.1) today, I got a prompt to download iphoto library upgrader. Once I downloaded the upgrader and ran it with iphoto, most of my photo/albums are not in iphoto anymore.

Does anyone know where I can find these photos (over 1000 photos from the past couple years)?

Thanks so much for your help!