How to recover files (images)?

Hi, I have a Nikon Coolpix camera and transferred all the pictures on there to my USB and then deleted them off the camera to save memory.
After a while, the photos wouldn't open and it says 'Photo Gallery can't open this photo or video. The file may be unsupported, damaged or corrupted'.
I have tried just about everything like downloading every recovery software, renaming the files, trying to change its format but absolutely nothing works as it continues to say it's 'corrupted'.
These pictures were very important to me. I have also tried to get back the deleted pictures off the camera but that also doesn't work because the camera does not show up on the software as there is nothing on it.
Any help at all is appreciated, thanks.

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