It sometimes happens that the USB drive does not work because it is not formatted properly. To me this has happened several times and I'm always in this case I use a program called GParted to format the USB drive and hard drives.
GParted is present in the Linux Mint software Manager, where you can install it or run the following command in terminal to install:
sudo apt-get install gparted
Insert your flash drive into the port on the computer and open the program GParted.
Now right click on the string with the USB stick, and on the shortcut menu, select Unmount:
Once your flash drive unmount, again right click on the line and now in the context menu to Format and select fat32 format:
Now you need to apply all our previous actions:
Your pen drive is formatted correctly.
In addition in Linux Mint has a utility called USB stick formatter:
I do not use, because several times after it had to re-format the drive in gParted. Use at your own discretion.