How to Access Invisible Files on WD My Passport?

I’m having a similar problem.  All of sudden my files are invisible as well but my disk management shows that I have 220GB used out of 930GB but I can only see 100GB files … other 120GB of files are there but not able to see. 

My pc is running on Window7.

Can someone help us retrieve this inaccessible files, please?

Your comments are appreciated.

Thnx