Make a folder without a name

 Click the folder, then right click on it, then click rename and delte the old name.

Then pressing ALT button from your keyboard and type 0160 after that press enter.

Important think to notice - you have to type by holding the ALT button, don't stop pressing and while you will type 0160 it will not appear.You should continue typing and then press enter. Another important thing is that you have to type the code (0160) by your numpad. If you type the code from the upper number key it won't work. So, make sure your Numpad key is on.