Cannot see or open a folder in my WD 500GB Passport

On 03July 2013, I found that I could not open a particular Folder in my external 500GB WD hard disk. Then again on 10July 2013, I could not open another Folder. It has never happened before since I started using WD hard disks from 14March 2011. All the other Folders/Files in my three (03) Passports (500GB and 1TB) are okay. (I never experienced such problem using Transcend pendrives or hard disks.) I then copied the two Folders into Document of my C Drive but still could not open them. When I right-clicked on the Folders to check the Properties, the number of files and the size were clearly indicated. A scan with AVG on the two Folders in both the external hard disks and C Drive and it clearly showed the presence of the Folders and Files. I tried with Recuva but no files showed in the tabulation table. I just do not know what to do. I would appreciate if someone could kindly share his/her expert advice. Thank you and regards.

When you click on the affected folders, does an error message pop up or does nothing happen? Depending on the contents of the folders (if they are just file storage or program dependencies) they may have had their contents locked by a program and this may have nothing to do with the drive itself since you said the problem persists after attempting to move them to another location. It is also true that the contents may have become corrupted and this is why you are unable to access the files.