the number one reason a fw won't make a stitch is because it is threaded wrong....
http://www.april1930s.com/html/upper_threading.html
http://sewingneedlework.suite101.com...sewing_machine
the other reason is the needle is set in wrong:
"The Singer Featherweight will NOT sew unless the needle is installed correctly. The problem is that the needle is installed on the Featherweight differently than almost all other machines. How do you remember the correct installation? There is a simple visual for you right on the machine! Look at the needle plate. Notice how it is shaped like a capital 'D'. This is EXACTLY how the needle is shaped at the top (end that goes in to be clamped). Make the flat sides match. Now you will be able to remember and 'see' how to do it every time you have to replace your needle! "
copied from:
http://www.novamontgomery.com/singer...-the-month.htm