Be absolutely sure that you are viewing hidden files. Click on View then Show Hidden Files. If you still get nothing, then you may have to resort to the command line (Terminal). Don't worry its not as scary as some make out. First make a note of where your usb stick is located. You may have to click the little arrow to find out exactly where it is


So in my example it my usb stick is called New Volume and is in media
Now open a terminal (Click the dash home button then type terminal)
Now you want to cd into your usb stick. So type (in my case)
cd /media/New\ Volume/
The \ is because I have a space in the name of my usb stick. You can also just type the start of the name, eg N then press tab and it should auto complete the rest
Once you are in there type
ls -a

This will show everything on you usb stick.
I have two directories (folders), .hidden and latest
If you get stuck then have a read of this:
https://help.ubuntu.com/community/UsingTheTerminal
Now if you can now see the name of the folder then it does exist and there is a problem with nautilus. Try closing the file manager (nautilus) and opening up again, or rebooting. If nautilus still doesn't show the data then you could try running this command
mv .hidden hidden
this will stop it being hidden and you should be able to see it with nautilus
If the folder you were expecting to see isn't displayed then you have a larger problem....