I am fixing a external hard drive for a friend (WD Elements) and it won't format.

When I plug it in my mac it only appears in Disk Utility (not in the Finder or on desktop) and there I can't do a single thing; it won't let me verify or repair disk permissions, it won't let me verify or repair the disk (all grey) and when I try to format or erase it, (and I have tried it many, many times) I always get that same message:
Partition(/Disk erase) failed with the error:Input/output error
and it says that the drive is a 2 TB but it is just a 1 TB.

So please,please help me.

Crossing my fingers for answers,
Eiður.
(see screenshots)