Why Can't I Play Videos I Uploaded They Use To Play!!!

I have a video titled Snowball Yoga it is my video of my dog named snowball doing yoga on a mat. it is mine now all of a sudden I can't see it. My dog snowball just died and I wanted to see what was mine what was so dear to me. Now it is gone and I would like to know why! I used an Android device to upload it. I used an Android device to try and play it since I tried with my Iphone. Many of my videos do not play. This is not right it was all I had of him while he was alive and I though it was safe to place that video with your website.