Method #1 (The Graphical Way)

Open Disks program from dash:

Then choose your device from left. Make sure you have selected at least one volume, and click on format as below:

Method #2 (The Command-Line Way)

In case you can't get your device formatted from Method #1 try this way.

1. Open the Terminal (Ctrl + Alt + T)




2. List your block storage devices by issuing the command lsblk
   
   Then identify your pen drive by it's SIZE. In my case its /dev/sdb

   
   
   

   




3. Erase everything in the pen drive (OPTIONAL):

   
   
   

   sudo dd if=/dev/zero of=/dev/sdb bs=4k && sync  
   
   

   
   
   

   Replace /dev/sdb with your corresponding device. This will take some time. It will pretend to stuck. Just be patient.




4. Make a new partition table in the device:

   
   
   

   sudo fdisk /dev/sdb
   
   

   
   
   
   
   
   • Then press letter o to create a new empty DOS partition table.
   
   



5. Make a new partition:

   
   
   
   
   

   • Press letter n to add a new partition. You will be prompted for the size of the partition. Making a primary partition when prompted, if you are not sure.

   
   

   • Then press letter w to write table to disk and exit.

   
   



6. Format your new partition.

   
   
   
   
   
   • See what is your new partition with a command lsblk
     
     In my case it is /dev/sdb1
   
   
   
   
   

   

   
   
   
   
   

   • Issue the command below to format the new volume:

     
     
     

     sudo mkfs.vfat /dev/sdb1  
     
     

     
     
     

     Please replace /dev/sdb1 with your corresponding device.

   
   

   • Eject the device:

     
     
     

      sudo eject /dev/sdb