I recently got a used computer with Vista Home Basic on it. Everything went fine last night when I first started it. Put my email account on it, etc. However, when I came home today and got on it, a window asking for my password appeared. It's my name, but I don't have any idea on what the password, evidently from a previous owner, could be. I don't even know how I got where I got. Now I can't get in the computer at all. Any help available?