Lock Your Hard Drive Without Password

go to folder options in any opened window,go to the second tab i.e VIEW tab...

go to last option i.e use simple file sharing.......tick it up....apply and close it....

Come to the My Computer window,now right click on any hard drive and further go to the security option and then allow or deny the permission of using that Hard Drive........

Further if u want complete denial then just remove the tick of the simple file sharing option.