1.first ,input your usb device on PC
2.then make any folder that maya contain your imp files which you want to be locked .
eg. here i make the new folder ERG
3.then open Notepad
4.Paste the following code:
set pass= ERG
set /p ui=
if %ui%==%pass% (goto open)
echo wrong password
5.where Red colour should be change by your OWN choice.
6.Now save the note inside your USB in .BAT format