USB Write Protection – How to Turn Off Write Protection on USB

I have a USB which is write protected:

dmesg | tail

[10098.126089] sd 7:0:0:0: [sdb] Write Protect is on
[10098.126098] sd 7:0:0:0: [sdb] Mode Sense: 23 00 80 00
[10098.126779] sd 7:0:0:0: [sdb] No Caching mode page present
[10098.126788] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[10098.131418] sd 7:0:0:0: [sdb] No Caching mode page present
[10098.131425] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[10098.133335]  sdb: sdb1
[10098.135509] sd 7:0:0:0: [sdb] No Caching mode page present
[10098.135515] sd 7:0:0:0: [sdb] Assuming drive cache: write through
[10098.135521] sd 7:0:0:0: [sdb] Attached SCSI removable disk

How can I turn the write protection off?

What I've tried

1. Checked if it has a hardware switch – no
2. Tried to format it on windows and on Linux (via terminal too)
3. Tried fdisk | chmod
4. Tried to fix this with several tools from Ubuntu software center
5. Used Google and have seen about 10,000 discussions about this problem but they were never solved

Additional information

fsck -n /dev/sdb1

fsck from util-linux 2.19.1
dosfsck 3.0.9, 31 Jan 2010, FAT32, LFN
There are differences between boot sector and its backup.
Differences: (offset:original/backup)
  65:01/00
  Not automatically fixing this.
Free cluster summary wrong (968250 vs. really 911911)
  Auto-correcting.
Leaving file system unchanged.
/dev/sdb1: 50 files, 93653/1005564 clusters

fdisk -l

   Device  boot.   Start        End      Blocks   Id  System
/dev/sdb1            32     8060927     4030448    b  W95 FAT32

umount /dev/sdb1

mkfs -t vfat /dev/sdb1

mkfs.vfat 3.0.9 (31 Jan 2010)
mkfs.vfat: unable to open /dev/sdb1