It's probably a bad stick, the write protection comes up as a red herring when usb sticks fail in some cases. If diskpart does not work on clean and format it, get rid of the stick and get another one. They are very cheap.
If it is a bad stick, it is better to buy a new one. No use spending too much time trying to solve on a bad or broken stick.
If you are trying to bypass someone else's write protection, nobody in this forum can and will help you.