If you send the drive to me I'll analyze it and get data out, but it's me
Sometimes if "some" part of FS in NTFS get corrupted (I am simplifying it) you have strange behaviours like - not limited to : you see the files but trying to access a folder you get "ACCESS DENIED" and there's no way (usual ways) even to DELETE the folder, or you get "Incorrect function" or when you launch an application ".... is not a Win32 valid application" or stuff like that.
I had myself "complicated" times fixing partially corrupted FSs even if I know (some parts are still obscure even to pros) how NTFS works.
I cannot point to anywhere without seeing the drive and analysing the FS.
I would ask you to check journal, protection descriptors and a lot of other things...
Probably you are searching a "click and go" stuff that fixes your problem. I have to give up and sadly I think it's more a question to put on other forums rather on technical HDD-related forum. Only if and when you are sure it's the drive having problems you can ask ONLY A 2nd OPINION here.
One thing is sure : it can be FS or a drive problem. In any case you need some intervention to get data back and only then you can try to erase the drive and see if it works again.