Where did you move them from and where did you move them to?
From different folders on the same drive. Thanks.
edit: In case that wasn't clear:
Since my camera shoots video in AVCHD, I use Sony software to import videos (and sometimes, accidentally, photos) from the memory card. These go in D:\PlayMemories. I like to keep everything in my lightroom catalog organized by date in D:\Photos. So, i'm moving the files from D:\PlayMemories to D:\Photos.
I haven’t heard of LR deleting files during a move-import, though if you have more than one catalog and the photos are in multiple catalogs, then they will be missing from the first catalog if you do a move-import using the second catalog, but they shouldn’t be gone, entirely.
Since you’ve searched your hard-drive I’d say they are gone, unless there is somewhere that your search didn’t look.
Is the D: drive something other than a second internal drive, like a NAS or network drive?