Can't unhide a partition

Thanks Pentagon. I don't understand what you mean by - only if not !
I opened Powershell admin and here's what it said

Windows PowerShell
Copyright (C) Microsoft Corporation. All rights reserved.

Try the new cross-platform PowerShell https://aka.ms/pscore6

PS C:\WINDOWS\system32> diskpart

Microsoft DiskPart version 10.0.19041.3636

Copyright (C) Microsoft Corporation.
On computer: Q9450

DISKPART> list

Microsoft DiskPart version 10.0.19041.3636

DISK - Display a list of disks. For example, LIST DISK.
PARTITION - Display a list of partitions on the selected disk.
For example, LIST PARTITION.
VOLUME - Display a list of volumes. For example, LIST VOLUME.
VDISK - Displays a list of virtual disks.

DISKPART> list disk

Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
Disk 0 Online 372 GB 1024 KB
Disk 1 Online 931 GB 0 B

DISKPART> sel disk 1

Disk 1 is now the selected disk.

DISKPART> sel par 3

Partition 3 is now the selected partition.

DISKPART> det par

Partition 3
Type : 07
Hidden: No
Active: No
Offset in Bytes: 88524980224

Volume ### Ltr Label Fs Type Size Status Info
---------- --- ----------- ----- ---------- ------- --------- --------
* Volume 6 F DATA WD 1T NTFS Partition 849 GB Healthy Hidden

DISKPART> set id=07 override

DiskPart successfully set the partition ID.

DISKPART> assign letter=F

Virtual Disk Service error:
The specified drive letter is not free to be assigned.


DISKPART>

According your screenshot
disk 1, partition 3 is the problematic one. Is that right?

You found
Partition 3
Type : 07
Hidden: No
if not means if you had found
Partition 3
Type : 27 for example that is not 07
Hidden: No

Pentagon said:

According your screenshot
disk 1, partition 3 is the problematic one. Is that right?

yes. I assume the first partition is called partition 0. In powershell it described partition 3 perfectly as my large data partition. What's next?

GerryPeters said:

yes. I assume the first partition is called partition 0. In powershell it described partition 3 perfectly as my large data partition. What's next?

No, that's wrong
the first disk is disk 0
the first partition is always 1

This is the original Microsoft Script to prepare the disk.
copy the file to C:\

disk1.txt

run cmd command
C:\Windows\System32>DiskPart /s C:\disk1.txt


after 5 seconds the disk is ready (C:) will be 75 GB

See the result in Diskmanagement

That's the professional way!

I use this script for years now and Microsoft doesn't use your instructions!

Pentagon said:

No, that's wrong
the first disk is disk 0
the first partition is always 1

I'm using Powershell, not sure if that's different terminology than CMD. BUt I tried calling it part 4 and it gave info for EX Part.

DISKPART> sel par 4

Partition 4 is now the selected partition.

DISKPART> det par

Partition 4
Type : 07
Hidden: No
Active: No
Offset in Bytes: 79553363968

Volume ### Ltr Label Fs Type Size Status Info
---------- --- ----------- ----- ---------- ------- --------- --------
* Volume 5 EX PART NTFS Partition 8 GB Healthy Hidden

DISKPART>

And why don't you use cmd?

I changed the drive letter to k

diskpart
sel disk 1
sel par 3
det par


In det par output

type = 07 ?
only if not 07 !
set id=07 override

otherwise:
assign letter=K
exit

reboot and see what happens.