External harddrive deos not show up any moor

Hello,
i buyed a baffaulo external usb harddrive it worked fine before but now i haw tried to put on a password on using they own lock ware software but now it deos not show up in my computer were it used to. but it deos works fine because i hear the sound and see the led flashing i dont now were it has gone please help me i am using windows vista it basicly brand new i only brought it a few months back