The photos are hidden activate show hidden files in explorer features. You have not lost them.
See my comment below
This issue is well covered here
A work around is mentioned here
and the good news a patch to fix this has been released to Australia and Korea areas last week and to UK and Canada english users today but that release had no fix included so will be re-released soon.. US users on 31 Aug. The release will be throttled so say 5% users in that area get the fix on day 1 another 5% days 2 etc.
The above link has a way to unhide the files.
I can see why some would be panicking. 20Gb wedding photos go missing.
For 'US users' read 'US users and the rest of the world'.