Missing files on SD card

[SueRoberts]

So I took pics yesterday on my D750 which has 2 slots for SD cards.  I took about 15 pics then took the SD card from the 1st slot out to view them on my computer.  I forgot to put that one back in and took more photos which then went to the SD card in Slot #2.  This morning I showed my husband a couple of the photos on the back of my camera and then went to my computer and placed the SD card to download them.  I performed the same ritual through bridge as I always do but this time the photos weren't showing up.  In the place of them was an icon with the picture of a closed aperture.  The file numbers were there followed by .nef but no photos!  So I took out the SD card and put it back in my camera to see if they would show up and I got an error message saying "Wrong file type" or something like that.  So I put the card back in my computer and no luck.  (Insert nauseous feeling here).  I googled SD recovery and found a program called Easeus which I ended up paying for and it did recover my photos.  Whew!  This has never happened to me before.  Obviously.  

So my question is:  Can anyone explain what happened here and is my SD card corrupt?  

Thanks

[Brian]

When transferring the images from your card to your computer, do you "Copy" or "Cut" and then "Paste?"

Do you normally delete in camera?

What Brand / Model SD Card do you use? How old are these cards?

[Brian]

Oh, keep this in mind:

YOUR CAMERA'S LCD IS A LYING AND CHEATING WHORE THAT WILL SELL YOU DOWN THE RIVER IF GIVEN THE CHANCE!

The image that you see on the camera's LCD IS NOT THE RAW FILE itself, but the JPEG Preview associated with the Raw File. That's why your images go from #amazeballz to #blaw when you view them in ACR.
 

[SueRoberts]

Hi Brian!

When transferring my files I go to FILE> Get Photos from Camera.  

I always format my cards when I put them back in my camera.

My SD card is a Lexar 32GB 1000X.  It is about 6 months old.  

[Brian]

The short answer that I can give you as to why did this happen: I don't know / Just because...

The long answer? I think it has to do with how the data is stored on the memory cells in the SD card, or the way the camera treats the cards. If you have the camera setup as "Overflow" instead of "Duplicate," when you remove the card out of slot one, the camera will automatically start using slot 2. Then you re-inserted the card in slot one. If you took photos with the slot two card, then went back to slot one, the camera could have corrupted stuff. The other thing is that perhaps Adobe Bridge did something to the disturb the files on the card, and corrupted things. 

I'm a bit of a purist. I NEVER let software do the import for me. I will manually copy the files from the card to a folder on my HD, THEN use Bridge or import into LR. In addition, you have to treat your cards like film. Pulling them willy-nilly and then re-inserting them may not always work in the end. You could have done this 1000's of times with no problems, except that one time that it bites you when you need images. Personally, I pull both cards out at the same time from my D3s when I'm swapping / viewing things and I never switch the card in slot 2 and put it in slot one. Or leave the card in slot two and keep shooting. My method is, two cards go in, and two cards come out. Period. When I re-insert those cards they are both formatted before photographing anything.