Why won't my memory card show up on my Camera Or my Mac?

When i put my memory card into my Nikon D5100 it says there's no SD card inserted, and when i put it into my mac it doesn't show up at all either. It has never done this before and i was in the process of taking off photos of my friends band. Please Help i don't want to have to shoot them all over again.

Try any of the recovery software below.

"It has never done this before"
Yeah, that's always the way it is. The first time something doesn't work right is always before it does it again… Huh?