I have a 16gb ultra sandisk flash drive, have used it for about four months now and out of nowhere when I plug it into a USB port on my computer now it asks me if I want to format it? Where's my data?
It is acting like it may have been unplugged without properly "ejecting" it from the computer, i.e. clicking on the little icon in the system tray before taking it out. Before losing all of your data, try using it on a different computer and see if it gives you the same message. If it does, you may be forced to format it.