Old iPhone videos won't play

Hi,

I am trying to view older videos saved on my iPhone but am unable to. The oldest video I can see is from October 15, 2015 but 61 videos saved before that date are not viewable except for 1 - which was edited from May 29, 2015.

I have never saved my media in iCloud so this has nothing to do with the cloud. I even went and viewed my iCloud photo library to confirm that nothing is there.

Does anyone know what happened? Why the older videos, recorded and unedited on older iPhones, are no longer viewable?

Do I have any recourse?

thanks