Desktop PC Windows 10 home 64b. purchased 5 months ago.

This has happened 2 times in 3 months:
An SD memory card was taken out of a DSLR after shooting 30 or 40 photos and inserted into the above said PC for copying the photos. A message showed up saying something like an unexpected error or mistake....
After this, the whole folder containing 30 or 40 photos vanished from the SD card. Nowhere could I or search find it. The same thing happened twice in about 3 months. Never experienced anything like this before Win 10.

The question:
How to find the lost folder and files therein?