My USB have a problem, Once i have cut & pasted the Full USB data to my office PC to give my USB to a friend for few minutes.  when he returned USB i copied my data from my office pc to my USB, but its not showing any files at all !!  when i checked the properties, it is still showing 2.5 GB space is used in my 4GB.  At the same time i cant see any files at all . Pls advise how can i view/get back my files in USB ?