Here I use Dropbox since each picture ends up in my Dropbox then I can take it from there on my PC. There are so many systems out that I can't know which you used before.
I dropped my Samsung Galaxy S3 in the sink and it is now ruined (presumably--it won't turn on). It wasn't the end of the world, because I was due for a new phone anyway, and I had backed up all of my stuff (or so I thought). I had thousands of precious photos on that phone, and I was paranoid about losing them, so I checked multiple times that they were getting backed up, and every time there was a check mark next to "photos" on the list of things that were being backed up.
I went and bought a new phone today (Samsung Galaxy S6) and everything was transferred from my old phone except no pictures showed up. I went to the Cloud and there were no pictures there. What happened?