Being very straight foward.
The data got corrupted some how (maybe a faulty FC, micror SD card or Micro SD adapter, etc)
What you can try is follow these steps to try fix it
1 -Get other Micro Sd adapter and try acess the files again.
2 -You may aso consider using a different computer it it is still damaged
3- Run a software to recover files and save in your pc (dont save into sd card to avoid overwrite anything)
If nothing resolve, the only remaing is format you sd card.
And before making use of it again, use a software to check your sd card health, it may be faulty or too old to
trust