Try a factory reset first.
Help, the photos on my LG K8 phone are being corrupted somehow, I've not done anything to the image but when I open it up it blocks out in grey so you can't see it and gets worse the more you open the image. This has been happening since January and has destroyed photos of my newborn son!
Not just happened on one LG K8 but my previous one as well, using a different SD card in second phone as we thought that could have been the issue, but it seems not.Click here for example<br>

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