SD Card not workng

I was writing lines to a text file at a fast rate with an arduino board. When I tried plugging the SD card into my laptop, it was not showing up. I tried other laptops and the arduino board as well without any success. This was when it was inserted directly into the laptop's built in SD card...

I'm interested in building a small form factor PC rather than buying one. My roommate's got a pretty sick deal on a lenovo m91 and I just want to know if I could build one for under $400? I have no real part list and no spare parts at the moment.