I have the same problem, there is something with the access of reading the SD that then appear as illegible (both the camera and the whatsapp, impossible to access from the gallery or from the PC), which occurs only when the default storage It was the SD card. The photos are there, but illegible. To solve the problem in the future, if you have Android 6.0 or higher it is easy to solve by configuring the SD card as internal storage (and placing the internal storage by default). But to recover the photos from the camera and make them readable I have not found a solution. If they were photos taken or sent by whatsapp, you can recover them by opening the web whatsapp on the PC (I have done that), but if they were in the gallery ... well I do not know. If your android is Lollipop (5.X), bad, I have not managed to solve the SD configuration.