WD external hard drive says "can't access files"

Hello, I have a WD My Passport External drive (2.0) and it no longer allows me to access my files. It all started when I was having issues with my computer so i placed all my files on the harddrive and when i got my computer fixed and  I attempted to place the files back on the computer it wouldnt work I’m not sure if I selected scan device by accident but now when I tried to open my files I receive a message saying No access. It seems as though the files are still present on the harddrive; is it possible for me to get my information back?

What OS are you using? Does the drive show in Disk Management? In Vista and Windows 7 you may need to change sharing permissions or take ownership.