micro sd usb drive!

i have a 2 gig and a 4 gig micro sd card and i am using the cyclo ds evolution reader. i upgraded from windows vista to windows 7. i put in the 2 gig sd and it came up for about a min. i started to delete a couple nds files and the whole folder closed. i cant find where it is now and when i plug it into a usb spot it connects and does the normal windows sound. the duh duuuuuuuh thing. sry only way i can describe it. anyone know whats happening?