this is probably caused by corrupted pendrive due to plugging it out without disconnecting the usb from windows.

Try run checkdisk. Open dos prompt. Then type chkdsk /f c: (or d: or e: depending on your usb drive alphabet).

Sometimes it will fix the corruption with some minor file lost.

Does the chkdsk produce and .chk file or folder? If yes maybe your missing files are there.

Or try this guide: http://www.raymond.cc/blog/how-to-recover-...k-and-scandisk/