SD Card needs to be reformatted every time it's inserted.

Hey, don’t run chkdsk if this is a result of hard drive damage, e.g. you dropped it. Chkdsk might further damage it. 

Try this, download and install a data recovery tool. I use iBoysoft for this. It has a free demo version and shows the preview of recovered files before purchasing!

Guide: https://iboysoft.com/data-recovery/raw-drive-recovery/the-disk-in-drive-is-not-formatted-usb-drive.html