Note 3 random pictures disappeared

[Atborad]

I had an accident on Aug 26th and took a lot of pictures. Today I needed to upload them for insurance claim. I went into Camera in Gallery but only a few (my vehicle) that I had taken the following day were there. So I looked in My Files in Images folder and I found some other pictures from that night (his car, none of the ones in Gallery). But not all of the many pictures I took. I emailed those to myself. Then I went back to do the same with the pictures (my car) that I found in Gallery, but they weren't there anymore. The ones that had been in my Images folder (his car) were there in Gallery now. I went back to Images folder to see if they (my car) were there but they weren't. I have 'show hidden files' checked. I haven't been able to sync anything to Dropbox since March of last year. I don't know if any of my other pictures are missing; of course only these very important ones I need. Android 5.0