undelete files on vfat filesystem

step 1: Delete your favorite files on a vfat filesystem in a usb-flash drive with command：cd /media/usbkey rm *
step 2: Unmount the filesystem with command: umount /media/usbkey
step 3: Try to remember the path of the deleted files, then undelete them with command: dosfsck -r -u

note: the path begin with slash, from the root of usb drive, not from the mount point.