i have a group project due friday and NEED help putting my video back to my dv tape.

for some reason my computer doesnt detect my camera so i cant capture anything or export back to the tape. it doesnt detect in movie maker, premiere, or pinnacle. ive tried firewire, usb, dv, and s-video plugs and none work, but they all work on my friends computer. anyone know why my computer would just stop detecting my camera? ive tried 3 cameras too?