Disk not seen by fdisk or gparted

I am ruing Ubuntu 15.10

A year ago I bought a fourth disk and installed as a single partion. Some time ago, it stopped working. It was still available from fdisk, but I could not mount it. Then I ran mkfs.ext4 with no errors. Now lshw -C disk gives for the drive:
*-disk:1
description: SCSI Disk
physical id: 0.1.0
bus info: scsi@1:0.1.0
logical name: /dev/sdd
configuration: logicalsectorsize=512 sectorsize=4096

It gives no vendor or product information and no size

The disk is now invisible to both fdisk and gparted:

sudo fdisk /dev/sdd

Welcome to fdisk (util-linux 2.26.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

fdisk: caot open /dev/sdd: "No such file or directory "(->translated to english)

This is a huge disk (3T). Is it defect? Have I used wrong tools? What can I do to figure out the issue(s)?

Pål