Memory card photos are inaccessible for not formatted error

This morning, when trying to access some photos taken last Sunday with my mum, I just found the attached phone SD card could not be accessed. Whenever I tried to open it, it would pop out a message saying: “The disk is not formatted. Do you want to format it now?” But, formatting was not what I wanted now. Do you have any idea to fix this not formatted error? What am I supposed to do for accessing my photos there? Thanks for any suggestion here!