I created a bootable USB stick on Windows. Then My USB storage capacity reduced to 2MB from 14GB.
Follow the steps from this link: http://askubuntu.com/questions/289971/usbs-storage-capacity-reduced-to-2-mb-from-16-gb
The following is the screenshot of what I did:
Now we can see that Used space and Free space both become 0 bytes:
We need to format the disk:
After formatting, we could see that the USB’s capacity turns back to be normal: