HD Mounted, light blinking but does not work

Hi all,
I have a WD 2TB hard drive. When I plug it in, the light flashes steadily and the HD shows up on the desktop, but it can’t do anything else. When I click it, it is able to show the folders inside but can’t go into the folders. It doesn’t show any warnings, it just shows nothing in each folder. If I leave one folder open long enough, it will eventually show whats in it.

I tried disk utility first aid and it says:
"Repairing file system
Volume could not be unmounted.
Restoring the original state found as mounted.
Unable to unmount volume for repair.

Operation failed…"

How can I troubleshoot this?

Thanks!