Can't Read CR2 Files...Says "It Is Not The Right Type Of Document"

Hello Everyone,

I'm kind of beginning to panic because I took hundreds of photos on a recent trip and uploaded them to my computer.  It seemed like everything was fine, so I deleted many (but not all) of them from my memory card in order to make room.

Upon returning to my computer though, I realized that every time I tried to open a photo, it told me "Could not complete your request because it is not the right type of document."  And when I went to other programs to see if they could view the files, it was the same thing--they said it was not viewable or workable in any way.

I tinkered a bit, and tried re-downloading the photos that were still on the card.  This time I used Digital Photo Professional to do the downloading, instead of copy/paste like I usually do.  Suddenly all the photos were viewable.  Indeed, when I sent the photos directly from the camera to my cell phone over Wi-Fi, I received a perfect jpeg every time.

So while I am grateful that I managed to save many of them, there are still a couple hundred that I have so far been unable to recover...some of which I would very much love to see again.  Any help would be greatly appreciated, and if anyone has an explanation as to why the files would be fine if I download them one way, but not another, that would be appreciated as well.

Some notes:

- I have completely updated all the Adobe CC programs and drivers to the best of my knowledge.

- I have a Canon 5d IV, and use a 128 GB Lexmark CF card

- When I look at the properties of the "bad" files, it tells me the right date, time, and even says it's a CR2 file.  But all the files are the same size, and it says that size is 28 GB, which is obviously huge (and wrong).

- I have tried converting them to TIFF files, to no avail.

Thanks in advance everyone...really appreciate the help!!