I have an SD card that simply will not mount; I've tried it in two Macs, two PCs, and two different card readers. I'm attempting to recover some images from the card; it was formatted in the camera and then had two photos captured and written to it. The strange thing is that if I insert the card into another camera, it works, as evidenced by the two photographs taken after formatting. Any thoughts on how to mount the card in order to run recovery software?
Hi there, as for the trouble that the SD card works well on your camera but fails to mount on your PC and Mac, I guess that it is defective. You can try to force mount it on Mac via launching Disk Utility > selecting your SD card > tapping on the Mount menu on the top menubar.
Once you mount the SD card successfully, use iBoysoft Data Recovery Software to start the files you want.
If not, check this article for more solutions: [Solved] How to Fix SD Card Not Mounting on Mac?
Here is a complete tutorial on how to reinstall Mac OS X or macOS Sequoia and earlier on your Mac without losing data, both Intel-based Macs and Apple Silicon Macs are covered in this post.
If you want to install macOS on Windows via VMware or VirtualBox, you can download macOS Catalina VMDK directly from this post and use the VMDK file to configure your Windows PC.