SD Card Problems. Please Help Urgent!

Hello,
I have a SanDisk, 1 GB camera memory card. For some reason my computer cannot detect it in the USB drive. I have multiple slots in my computer, and the card fits perfectly in the slot. The slot is even labled MM/SD. The card worked perfectly fine at my friend's house, so I'm not sure why it's not working now. When I put it in, a green light lights up just like it does for my other memory cards. The only difference is that my computer shows no signs of detecting it, and the light flashes continuously instead of staying solid. Please help me as I need to download pictures and video for a science project I have due tomorrow. I've already been given a whole extra week, (it was due last Friday) and I have to turn it in tomorrow or all my hard work would have been for nothing. Please help! Thank you!