This is the most common and problematic reason why a machine stops sewing, a needle can get damaged or broken after so much use. The only solution is to replace the needle with a new one, it would be better if you change the needle after every project.
You need to make sure that the drop-feed setting of your machine is disabled, and that the feed dogs are not covered by any embroidery or darning plate. You will also need to make sure that the presser is not up and the pressure is set according to the fabric.
Another reason why a machine usually stops working is because of the broken thread. The solution for this is to use a heavy-duty thread that is suitable for the machine. The weight of the top and bottom thread should be the same and of high quality.
You should make sure that the bobbin of the machine is inserted correctly. The bobbin should be inserted into the inner rotary hook. So, the thread is behind the bobbin spring of the inner rotary hook and it is flat from the bottom.
Most of the time the motor of the sewing machine stops working if you face this condition make sure you check the power cord that is plugged into the wall and machine. You should also verify that the wiring and fuse are not damaged, and make sure that the power strip is on.
Your machine may stop working because of the wrong tension of the thread. It is very important to set the thread tension according to the fabric you are sewing. And if you don’t do that, it can remain uneven and can cause your machine to stop.
The sewing machine is a sensitive product and can stop working even due to a slight problem, but there is no need to worry because its solution is very easy.