Don’t know what you were using for file restore but you could try a freebie called Recuva.
https://www.piriform.com/recuva
Also, if the file was somehow corrupted, it could be on there unrecognized, since the display will only show the file types it knows. Have you connected in both MTP and MSC mode (Settings/System Settings/USB) and looked for files from the date of the recording?
