thanks but that's not solving the problem that my brand new USB stick isn't usable anymore. I wanted to use it just for the win install and then take it as my daily stick for work because of the very nice form factor but right now I neither can install win nor reformat the stick and reformatting the stick is my main goal here, that's why I'm asking.
AND I want to warn people that following the guide of the opener can bring you into such a situation where I am right now.
Got it back to life!
Here is what I did:
open terminal and enter
diskutil eraseVolume HFS+ USB disk2
"USB" is just the name, you can replace it with anything you like or you want your formatted thumb drive to be named. I called it USB for example.
"disk2" refers to the position in the device tree. To check the position of your faulty thumb drive go to diskutility app an click on your thumb drive and look at "device" in my case it said "disk2".
hit the enter key and it shows:
Unmounting disk
Erasing
Initialized /dev/rdisk2 as a 29 GB case-insensitive HFS Plus volume
Mounting disk
Finished erase on disk2 USB
enjoy your perfectly working thumb drive