I was working on a digital drawing about 8 days ago and decided to work on it a bit more today, when I tried to open it on Photoshop it said that it was not a PNG file, despite the fact that I did save it as a PNG. (The file is even listed as a PNG in my folder.) This is the only file that isn't opening, I can't even view it in a photo-viewer. For some reason it saved itself as a PNG image, I didn't import it as such and I definitely didn't save it as such. The file was fine the last times I used it, now all of the sudden it doesn't work. There is nothing I can do to open my file. I can't view or open it with anything but I can see the preview for the image when I open Photoshop. All of my other files are able to open.