For less than a year my wife has been using a ZenPad80 tablet running on an Android type OS from new and has taken a number of photos and videos. Yesterday she noticed that none of the photos or videos appeared to be found in her "gallery". Eventually she found some of the files in a google location, some photos cannot be displayed (show as a blank canvas in the gallery-style panel) others are completely gone and there are no videos at all. The missing ones are apparently a completely random loss in a chronological sense but they do appear to be missing in groups as everything from a particular occasion is gone but those from occasions on either side may still be there. These patches are scattered across the timeline and bizarrely in her own gallery, where everything originally was, she now has only the very first photo she ever took and then yesterday's test shot using the camera after making the irritating discovery.
Having up to yesterday accessed the gallery as normal and noticed nothing untoward, she yesterday only changed the locator from what it was (we are in a different country) but otherwise has changed nothing and done nothing apart from checking e-mails and carrying out innocuous browsing. She certainly has done no deleting and there is nothing in the "recycle bin".
Can anyone suggest what has happened and how to recover the missing material which presumably is still somewhere on the device ? She has no backup of anything apart from in her archive from whenever she sent something as an e-mail attachment.
Stop press: The whole lot is back where it was - and it always was. By shutting down, removing and reinserting the SD card, and then booting up again everything was restored. It would appear the card was not detected/engaged. Everything is now backed up. Thanks for suggestions.