Hi, Allan
I have seen many cases, where users can not see the content of their external drives/pen drives without any particular reason, but they can confirm that the space on the drive is used, meaning that the files are still on the drive, but can not be seen. Sometimes this happens after OS updates, because of HDD issues, software issues, anti virus restrictions (after an update) or ownership changes. Some of these may happen without the authorization of the user (like auto updates). I think the files are actually there. Some users report that taking ownership helps, so that is why I suggested it.