I upgraded to MAC OS Catalina and I lost my IPHOTO program with all my photos. How can this be fixed?

Launch Photos with the option key held down. It will allow you to choose your iPhoto library and create a new Photos Library that will let you access your media. Your old iPhoto library will not be changed.

launch PHOTOS* with the option key held down, not iPhoto.

*The icon looks like this:

I hold down the OPTION key and launch iphoto and I'm told that this app is no longer available. Please help as I have lost all my photos

I Did the same. The option s key worked after hours of trying other ways. Do I need to do that every time or can I get them on Catalina version?

Once the library is converted into a Photos library, you just use Photos with that library as your main library, no further conversions required.