Just wondering if it can be done.. I know cropped photos can be recovered but I'm not sure about a PNG file.
As far as I know cropped photos can only be recovered if you have saved the layered file version and used the crop tool to hide the cropped off area not delete it. That would be the same for your png if you have saved the png file layer document version. Your not going to recover cropped off areas from a jpeg or png file the data is not in that file.