Alright so my computer just crashed and my USB was in the port. After I rebooted I tried to access my usb, at first it asked me if I wanted to view the files but when I clicked view files it told me the there was no USB in the drive. So I tried the USB on another computer and the same thing happened. About an hour later I tried it again and this time for a second the USB showed up on My Computer, and I could go on it and see all files were still intact, But after a few seconds the usb disappears and I can no longer access it. Does anyone know what happened, and what I can do without having to reformat and delete everything on it??

When you have the USB device connected what does it show in device manager? does it show with any error when it's working or not working?