plug in the SD card to your PC, from there you click START, click MY COMPUTER, there you should see a list that says (C:/) and the disk drives (E:/) and all that, at the bottom of the list there, it should say SDHC or KINGSTON or whatever brand your using. Right click the SD card, click explore/open. now there should be your files and folders.
If the SD card isnt in the MY COMPUTER part, then either the SD card is bad, or the SD is too large to run in the port you plug it in. if its directly into the desktop, and it isnt recognized, then i recommend you buy an adapter from SD to USB. and plug it in that way.