your machine will have a flip type opening at the very front of your machine above the area where the needles are attached to the arm that moves up and down ( it usually has the light globe installed in there ) after opening that door you will see where the dog feed is attached to it should also have a spring that helps the dog feed return to the up position when not in use , make sure it is not stuck in any way and some lubrication oil should be used to prevent it from sticking , while using the dog feed release button push the spring in a up and down motion to help it to dislodge
You need to explain what is it doing. Stitching need a thread properly coming from reel above and going thru the needle. And a thread coming from bobbin under the foot. If you know how to properly guide the thread let me know what is it doing.
It has happen to me with my machine, either you did not thread your machine right or the bobbin. You need to rethread your machine and make sure that the bobbin is threaded right too. It can be very frustrating!!
There is a zig zag gear in the top of the machine that breaks somertimes and thus prevents the machine from working correctly. Or it could be the machine hasnt been cleaned and lubricated properly.