THE SEWING THREAD WILL NOT CATCH THE BOBBIN THREAD

This means the rotary hook is not catching the top thread and looping it around the bobbin.

Be sure the needle is not bent and top thread is properly threaded. Be sure needle is properly oriented and seated in the needle bar.

Be sure you have bobbin properly wound, inserted, and threaded per machine instructions.

Download your owners manual from the Singer website at...

https://res.cloudinary.com/singer-sewing/image/upload/fl_attachment/Singer-Website-Library/outdated_product/3cf22829df0e29cefa14c8141bd10ddccf20d614_0.pdf

Try cleaning hook and race area if still having trouble.

If it was working fine and it recently broke a needle and/or jammed, the timing may have slipped.

Do you have the bobbin in correctly? Clockwise or counterclockwise...
Is the needle in correctly? It could be backwards.
Rethread the bobbin if the thread is not wound on properly...too fast makes the thread too tight, too slow and it can wrap onto the bobbin in a haphazard way.
Check to be sure have the correct needle for your machine...matches stitch etc..
If your machine is electronic...turn it off so it goes back to any default settings.
seems like a lot, but one little thing...

hi Shauna.
this is all i could find out from the internet.
Make sure the presser foot is up when seating the thread through the upper tension. Now, it's time to draw up your bobbin thread. Turn the hand wheel (TOWARDS YOU ONLY, never turn the hand wheel away from you) and hold the needle thread lightly. Tug on it as the needle goes down and then comes up again.
if this is off no help to you go to this link and see if its any good to you.
Frequently Asked Questions Singer Sewing
or this one.
Sewing Machines Won catch bobbin thread Google Search

That is called "thread nesting," and several things can cause it. The upper thread enters the bobbin area during sewing, catches the bobbin thread, and as the needle goes up, pulls the stitch tight. Something is catching the upper thread as it goes around. The most common reasons are the bobbin or bobbin case (or both) is improperly inserted; the bobbin is warped (roll it down a flat surface--if it wobbles, it's warped), either the case or the bobbin is not seated evenly, there is a rough spot on the bobbin case that is catching the thread, or your bobbin is loosely/badly wound. You need to rule out the possibilities step by step until you find the cause. First, review your threading procedures from start to finish, using your user's manual. Then, without fabric, turn the hand wheel by hand (ALWAYS towards you) to see if you can see it start to catch. The top thread should rotate smoothly in the bobbin area. You should be able to pin-point the cause that way.

Service Timing is NOT a home fix

hi, you need to alter the timing, mostly related to the upstoke, as the needle returns, sadly i never worked on one of these however it sounds a classic timing issue...

Regards
Rob

www.electronicrepairs.co

Check the bobbin tension and timing. Please top and bobbin using to new quality threads.

needle's in backwards

there are a couple of things that come to mind.  
Bobbin:   wound with uneven tension.  Try taking the bobbin, rewind that thread onto another bobbin and wind slowly.  make sure the thread feeds onto the new bobbin evenly.
upper thread:  catching on something or not flowing off the spool easily.
you're doing well, sounds like you consulted the manual and used your noggin, hang in there and let me know if this doesn't help.  we can troubleshoot some more!

Sounds like you have to take off the throat plate and clean out threads under it.  Sometime they ball up and prevent the needle from going down and catching the bobbin thread. You can't see themuntil you take off the plate.  Follow the directions.  It is easy.