Nikon / canon cf card mix up missing photos

I have a canon 7d, i took out my cf card and put it into my friends new nikon camera and snapped about 50 photos that i really need. And now i come back to plug them into my computer on lightroom 3, and they just don't show up nether do they on the finder of my camera.

any ideas how i can get these photos, or are they gone forever, can i recover them?

thanks for your time ill make sure to rate all your answers!

The image files on the Nikon are in a different file folder than the ones where the 7D images are located on your memory card.

And of course you can't see the image files shot with the Nikon on your 7D. The 7D only sees the images that it took and no other.

The sub directory that holds the NEF files will look something like this: 101ND800

You can't see Canon files in Nikon cameras. The reason for this is that cameras are not viewers. The files are there. Look them up in the computer.

STOP
do not write anything to your camera's SD card, otherwise you willt re-write the files and permanently lose your photos.
Install this recovery software called Tenorshare Data Recovery.
From inside the software, navigate/choose your SD card letter( "D", "F", "G"? ) and scan the section where it says "Deleted Recovery". Scan the card and Set the destination folder(folder where recovered files will be saved) somewhere on your computer.
BTW, you can get this photo recovery software from any-data-recovery.com It will show you thumbnails for your pictures that it found on your card.

Please plug the cf card to card reader and connect it to PC, scan the cf card with card data recovery software and recover photos.
For CF card recovery software, i suggect you use Card Data Recovery, which is a professional picture recovery program.

Wish that can help you!

I had success with this:
1. Do not save any new file to memory card.
2. Connect your card to computer. You should see memory card shown as a drive letter (like H. In My Computer.
3. Download recovery software, recommended one is this photo recovery (simply because i was using it and it worked)
https://t.co/zRidaP6n
4. Install and open the photo recovery program, select your memory drive, and click 'Start' button to start scanning process which will find your deleted photos.