I have a problem with a usb memory stick. Until the other day it worked perfectly well, now all of a sudden it won't let me access anything on it. When I try to open it I get a box which says that it isn't formatted, if I try to format it I get a box which warns me I will lose any data on the stick. In properties the file system has somehow changed from fat to raw, does anyone know of a way to cure this? The manufacturer's and Microsoft's help website haven't be able to solve it so far.