Unlock f drive from folder lock version 7.5

Hello,dear friends, i locked my f drive in folder llock by mistake. it contains very important documents. i tried to unlock it but i couldn't. it's saying that f drive is not accessible. may be there was huge amount of data(150 gb). that's why there is some problem but nothing is working........
plz help me guys plzzzzzzzzzzz........
it's very important