I have installed both windows 8 and Ubuntu 12.04, in separate drives. i am using 2 other drives commonly between 2 OS to store the data. if i copy or use those files with Ubuntu,later if i tried to use those from Windows 8, those files are disappearing from the disk. if i switch again to Ubuntu,then also i am unable see those files. and i seen the disk free space availability, that showing including those files,so i changed disk properties to show hidden, .extension files, then also i am unable see those files in both the OS. may i know what may be the reason and how may i get back those files?