Welcome Chaaaa
We like pictures
not only to see the different machines, but also be able to help. They usually need to be resized to be able to post.
I'm taking a guess that it might look like the one in post #134 of
Vintage Japanese 'Badged' sewing machine with fancy stitches
If you do
not have a manual and that
is like your machine you can find a manual that will help at at
http://www.singerco.com/support/instruction-manuals and put "W231" (without the quotation marks) in the search box.
If yours is like the machine linked to - Is the needle inserted with the flat side of the needle on the right side and are you threading the needle from left to right? Also, is the bobbin threaded correctly and seated correctly under the spring?
Janey - Neat people never make the exciting discoveries I do.