My SD card slot doesn't work

My SD card slot on the latest MacBook (Mid 2012) won't mount my SD card. The SD card doesn't appear in Finder, Disk Utility, Image Capture or anywhere. I know it's not a software problem, because nothing changed before and after. How do I fix it?

Solution 1:

I blew hard in the SD card hub. Now it is working fine.

Solution 2:

This thread says that there's a switch in the SD card slot that detects when a card is inserted, and it can get clogged by dust or jammed or something. If you play around with a toothpick (or anything that fits in that hole), it'll fix your problem. Toggling that switch helps.