Clicked "stop" when moving files and now they are gone

Thanks for the information.

Have you given permission for Bridge to access external drives (aka all drives)? 

As long as you've not used that card for any subsequent shooting, you should be able to recover all images with the use of a card reader recovery application. I cannot recommend one (I've not needed one and therefore have had no personal experience), but a search on the web will show several. 

Just a word of caution: I'd strongly recommend AGAINST, working on images that are still on a card reader. While you may get away with it a number of times, I see issues such as yours more often than I'd like. The safest way to work with images on a card is to get them onto your computer, AND THEN cull, fix, adjust, whatever you need or want to do. My basic process is to shoot, get the images on my computer, back up the images, then erase the card in the camera (not by the computer — that's important).

Just in case you need it, here's how:

Go to your System Preferences and select Security and Privacy (found in the top section). Now click on the Privacy setting (last tab). Now click on the lock on the bottom left and provide your Administrator code. Now select the Full Disk Access option and click on the "+" symbol. This will bring up the standard Mac Open window and let you add any application you want or need to have full access. Look for Bridge, select it, it will now appear in that window and make sure it's checked. Next, go to the Files and Folders option and do the same thing as above (although there's nothing to check, just add. Close everything down and see if that makes it all work.

Please let me know

[Note: these images are from an older OS, the process is the same.]