Welcome to Android Central! How are you trying to move the files, and are you getting any error messages?
Are you certain some of those photos or videos that were lost were on Internal Storage, or were they all on the SD? SD cards are notoriously unreliable, and should not be the only place you store important data. The SD card could be corrupt, defective, or counterfeit. Install
SD Insight to see if the card is genuine or counterfeit. Counterfeit cards are programmed to report more storage than they actually have, and if you try saving more than the card can actually hold, then files can start getting corrupt. (Be aware that SD Insight might not work on all Nougat devices.)
If it's a valid card, then go to
Settings>Storage, Unmount the card, remove it, and insert it into your computer. Can the computer read these files? Backup as much as you can right now, then run chkdsk to look for bad sectors:
http://forums.androidcentral.com/am...guide-using-chkdsk-fix-corrupted-sd-card.html.
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