Videos disappearing from Gallery after download

[Alexandra-kite]

Hi all,

A few nights ago I went way back through my OneDrive and downloaded heaps of old travel videos, perhaps 80 or so.
They downloaded no problem and appeared in my phone Gallery. 
I created a few new albums and moved and sorted the videos accordingly; all the files were there and worked fine as I showed some of the footage to my family the following day.

Now, all of the downloaded videos (from OneDrive) are gone and the only ones displayed in the folders are ones that are saved in other locations on my phone. 
I have checked Samsung Cloud and I don't have autosync on for Gallery, so they haven't been moved to the trash bin.

Any idea where my videos have gone? It's like they have 'un-downloaded'.
And can I get them back without having to scroll through my entire OneDrive again? It took me hours!

Thanks,
Alex

[TessM]

Hey @Alexandra-kite ,

let's have a look into this together. Can you please go to the apps' drawer> Samsung> My Files. Are you able to see these videos there? 

[Alexandra-kite]

Hi Tess,

No, they have disappeared from My Files also! 

It's like they've 'un-downloaded' from my device. 

The originals are still on my OneDrive so they're not entirely lost. 

[TessM]

When you downloaded them, did you save the files on the phone's internal memory or an SD card? 

[Alexandra-kite]

Internal memory (and I still have about 80gb free space).

I don't have an SD card in at the moment