sometimes lifting the foot up and turning the needle control forward and backward (not actually piercing the work), whilst you "gently" pull your work out is enough so that you can cut any unwanted cotton holding the work on the machine. This type of jam usually happens when the machine is working in the same spot, not advancing. You may want to check on the serrated "lifters"..the parts on the machine arm which lift up and move your work forward or backwards. They sometimes get filled with all sorts of fluff and scraps.. to get to them you may have to unscrew the top plate on the machine arm (where the needle inserts)give them a good cleanout with a brush, then oil them with machine oil.
I don't know the specifics of your sewing machine, but a couple good things to check on any sewing machine.
Is the foot up? If it isn't, there should be a lever to raise it up.
Is the needle out of the work? If not, there's a knob on the machine that moves the needle by hand. It's usually on the right hand side of the machine.
Hope one of these helps you.
It might be the piece in the needle plate that makes a rolled edge, if it is extended without the proper presser foot in place it can cause a jamb, usually you will get broken needle (s) also. the loopers are taking ties on the rolled edge piece and not the material and quickly ties down the fabric in the machine, or it just might be threaded wrong and the machine can't figure out what it is doing it gets lost in its own operation so to speak
When I've had this happen, I've had a 'nest' of thread under the material which is jammed into the needle plate. What I've ended up doing is removing the needle and the presser foot and cut the needle thread (to have more room to work) flip up and remove the needle plate and cut the bobbin thread. Now you can take the 'mess' in your lap and start trimming away that lump of thread under the needle plate. Depending on how much extra thread you have you may already have a hole in your material. Just do your best to fix it.
Now what caused the problem. Your needle thread was not threaded correctly. (Sound like it should be the opposite, right) Rule of thumb is if you have a problem underneath, the problem is above and if you have a problem with the top thread the problem is the bobbin.
Good Luck and happy unsewing.