The hard drive is a WDC WD40EZRZ_00GXCB0 4 terabyte. When I originally installed it, for some reason my BIOS only set up 3 terabytes. The fourth has been sitting there unused for 3 years and I'm tired of looking at it.
I have tried to establish a new partition with it but Windows will not deal with it. It won't format it, won't even access it. I'm using Windows 10 if it matters. I'm not using 11 because I won't use any new version of Windows until at least one service pack arrives. I'm not a beta tester.
(Rant over) Is there a utility or something out there that I can use to get this partition usable?
thanks1

Worth a BIOS update before you go any further, may well be that straight forward.

As for Service packs, they went out with Windows 7, but your right about 11, it's "not very good" to say the least.
The number installed is still less than 20% of all Windows machines, 10 holds the lions share...

Whatever they call the bug fixes these days, I wait until there's whole passel of 'em, if I ever upgrade at all. I used 7 Pro forever.
Anyway, the BIOS is the most recent version. This is a different computer from the one I originally set it up on, much newer, so it seems to me there should be something I can do to reach this dead space.