Most times you don't even need to format your USB stick. Simply delete the existing files and copy in new files again.
People usually reformat when they want to clean out the pendrive. Or switch from FAT32 to NTFS or exFAT to suit a particular OS. In my case, I was using Rufus to install a bootable ISO to my USB stick. For some reason, it failed during the creation of the partitions. Ended up with a pendrive that is not accessible. Right-click, Format. Windows says no. Tried using the excellent HP USB Disk Storage Format Tool. Says disk media is write-protected. No write-protect switch anywhere on the pendrive.
Now, the forums said that I should use diskpart to set "attributes disk clear readonly". Didn't work. Some suggested using regedit to create a new DWORD called WriteProtect under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies and set it to 0. Didn't work.
What eventually did work - using diskpart to create and format the active partition on the USB stick.
Here's the session log:
Microsoft Windows [Version 10.0.17763.316]
(c) 2018 Microsoft Corporation. All rights reserved.
C:\WINDOWS\system32>diskpart
Microsoft DiskPart version 10.0.17763.1
Copyright (C) Microsoft Corporation.
On computer: DESKTOP-46R9F1I
DISKPART> list disk
Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
Disk 0 Online 465 GB 1024 KB
Disk 1 Online 7646 MB 7645 MB
DISKPART> list disk
Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
Disk 0 Online 465 GB 1024 KB
Disk 1 Online 7646 MB 7645 MB
DISKPART> select disk 1
Disk 1 is now the selected disk.
DISKPART> list disk
Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
Disk 0 Online 465 GB 1024 KB
* Disk 1 Online 7646 MB 7645 MB
DISKPART> clean
DiskPart succeeded in cleaning the disk.
DISKPART> create partition primary
DiskPart succeeded in creating the specified partition.
DISKPART> list disk
Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
Disk 0 Online 465 GB 1024 KB
* Disk 1 Online 7646 MB 0 B
DISKPART> select partition
The arguments specified for this command are not valid.
For more information on the command type: HELP SELECT PARTITION
Partition 1 is now the selected partition.
DISKPART> active
DiskPart marked the current partition as active.
DISKPART> format fs=ntfs
100 percent completed
DiskPart successfully formatted the volume.
DISKPART>
After that, the USB stick works normally again.
