My iPhone 6 'died' on 20% and I turn it back on to find half of my photos are gone, anyway I can get them back?

My iPhone has started freezing at random times and shutting off by itself before coming on by itself, it did this twice earlier and the second time was when I took a photo, it wouldn't let my view the photo, shut down, came back on and I had 0 photos, they slowly started coming back but I only have less than half of them