All of my events have disappeared in the new Photos app for OSX Yosemite I have just upgraded OSX Yosemite and have been looking at the new Photos app.  It seems all of my events have disappeared.  How do I get them back?
The best option for working with events is to use the sidebar (cmd + alt + s or view → Show Sidebar). They will be listed there:



Without using the sidebar they are listed in the Albums section: