If the unit were a simple storage drive, files may be recoverable through software
recover utilities; especially if the unit were not used after realization those files
were missing or not seen by the directory, etc.
The device may have overwritten the content, especially if the unit were initialized or
re-set; one iOS device can remotely erase another iOS device, via in Find my iPhone.
If there were iCloud storage options in use as backup, if not overwritten or purged by
another device who may have shared the same storage, it may be recoverable. Also
if the option to save a backup via USB to a computer via iTunes, a chance there too.
•Get help with iCloud - Apple Support
•Change your iCloud feature settings - Apple Support
• iCloud Frequently Asked Questions:
http://rfwilmut.net/notes/icloudfaq2.html
•How to Turn On Photo Stream and iCloud Photo Sharing - lifewire.com
Not sure what options may be open to attempt a recovery of files, nor how they may
be found (if by file type or name, when connected by wire; and searched as though
the iOS device were an external drive) and some options that may exist may be viewed
as a form of hack. So that may not be an acceptable idea nor any official option here.
Perhaps someone else may consider these matters and offer some alternative suggestion.
At any rate, sorry to not have a workable solution. I do have & had tried data recovery from
external storage drives or macs who did not start, by use of free 'third party' utilities.
Ones that only look for files by name, perhaps something along this line:
Rather technical + not recommended. Certain file types may survive delete tags in an OS.
{The odds are against recovering files in such a small storage - when in use by the device.}
In any event...
Good luck & happy trails! 🙂