Q: We just updated to OS X El capitan and after that we cent find all photos we saved. Is it possible to find them?

Where did you save your photos before the upgrade?  Have the photos been in an iPhoto Library?  You can open your iPhoto Libraries in Photos for Mac by dragging the iPhoto Library from your Pictures folder to the Photos icon in the Dock.  Photos will migrate your iPhoto Library to a new Photos Library.     How Photos handles content and metadata from iPhoto and Aperture - Apple Support