Photo thumbnails can no longer be seen I took some photos and when I went back to look at them the thumbnails are black and corrupted.
How does this happen and can they be repaired?
Assuming the original photos are still available, the loss of the thumbnails is not an issue, so you can dispose of the corrupted files. The Gallery app will read the images directly. In fact, certain space-management apps will delete thumbnails for space recovery. I use SD Maid, which recommends their disposal in the SystemCleaner panel. I have done this a number of times, without system degredation. The Gallery obviously still works, as I can still find and display any of the near-1000 images taken on my phone. If you choose not to use SD Maid to clean them up, you can do this manually with any File Explorer app to find them in the DCIM\thumbnails folder. This folder is the sibling to the Camera folder (DCIM\Camera). Select and delete all the thumbnails without a problem, just don't do the same to the original images until you've backed them up.