I used this software called "USB Security" to password protect my files, but it ended up being permanently hidden because the cord was moved during the time where the flash drive and the SD cards were inserted in the PC, and just like that my password did not work. My files were hidden and even if they are supposed to be intact because they're just technically hidden and not corrupted, I was not able to recover some of the the large video files that I have, considering that they were not overwritten at all. I guess videos are indeed almost impossible to recover. Never again will I use a software to password protect my files. I also think that maybe your SD card got damaged at some point to the point that it could not read your card anymore, since I know they are resistant to scratches.