I tried to fill the bobbin with thread and it does not turn. I have used my machine for years and this has never happened before. I tried several bobbins and none worked. Hope you can help.........Sandra

Hmmm, could be several things.
Try a brand new needle. Try a different brand of thread.
Remove the top thread from the machine. RAISE the presser foot and rethread from the beginning. Verify the thread path is correct.

If it still will not pick up the bobbin thread, the machine could be out of time.

the thread is pulled from the bobbin by the sewing action of the needle passing the bobbin hook
all you have to do is fill the bobbin , place it in the bobbin carrier , pull the thread down the slot under the flat spring and leave about 6" free
put the carrier in the machine and turn by hand several times and you will see the bobbin thread come up with the needle thead

This happens to me when my bobbin isn't pushed down completely onto the bobbin holder. Also, it happens when I overfill the bobbin and the bobbin sensor doesn't stop the bobbin when it is full.

What kind of problems are you having?

The newer plastic bobbins can be damaged and end up with little burrs that catch the thread briefly and cause problems. Also check your thread spool... is it catching the thread and going zing and winding the thread around the spindle? (tension problem right there.) I use a thread sock to prevent this on my industrial machines. But I have noticed that this sometimes happens on my domestic machines too.

when you sew keep a eye on the thread take up lever & see if the thread comes off while your sewing, I've had this happen to me & I've been sewing for over 30 years. if this does happen, take a pair of pliers & very gently close the take up lever just alittle but not enough to damage it.
also check the needle to see if it's damaged--if your not sure change the needle--flat side goes to the back of the machine
always make sure the fabric & needle & thread are compatable--the thread must be able to pull thru the needle with out any problem
also check to make sure there are not any burrs on the needle plate or bobbin or bobbin case

I've had that problem before, I wrap several loops on the bobbin it's self & as I start to wind I make sure the thread from the spool is pulled tight from the spool to the bobbin,,& that usually takes care of the problem

Double check to see if the bobbin is in upside down and the thread is feeding from the bobbin spool in the wrong direction.

I did this once after several years using the same machine, some days are just not as easy as they should be!

There are a couple things that come to mind. If your plate is not pushed all the way up where it engages the metal tab on the bobbin, it will not wind properly. Second, if you are using a generic or an old bobbin, you need to replace it. I have seen many machines drive the owners crazy and it turned out to be a bad bobbin.

Use a SA 156 metal bobbin (ebay, 20 of them for $8.99 free shipping) and make sure the bobbin thread is turning the right direction, read you manual or call singer at 1-800-4singer

Divot on needle must be installed facing bobbin case.