The best way is to open the pen drive in a Linux based operating system. In case you do not have a linux based OS, then you will have to try to find the cause of inaccessibility in windows. In case it is due to a permission problem, you can try opening the pen drive in administrator mode.
Como Formatar meu pendrive Pelo cmd?
Formatar pendrive usando o Prompt de Comando
Digite cmd na caixa de pesquisa do Windows e, em seguida, pressione a tecla Ctrl + Shift + Enter para iniciar o Prompt de Comando como Administrador.
No Prompt de Comando, digite diskpart e pressione Enter.
No DISKPART, digite list disk e pressione Enter.
How to fix "USB drive not formatted” error?
Select the USB drive to format. Connect the USB drive or pen drive to your computer. ...
then click "OK".
Check the warning box. Click "OK" if you see the Warning window. ...
Apply the changes. ...
Do flash drives need to be formatted?
USB Drive Says Needs to Be Formatted. USB flashdrive says needs to be formatted: when plugging USB flashdrive to a computer, it is recognized as an external device. However, when clicking on the flashdrive, it cannot be open or accessed normally by showing an error message "disk in drive is not formatted do you want to format it now".