Hello Maureen,
I think you will find that you have something stuck in the raceway area such as a small piece of thread, take out the bobbin and bobbin case, if you have a drop down gate once you have taken the bobbin case out then drop it down and take out the hook that is the half moon shape, and have a good look and wipe it, with those parts out you should be able to turn the balance wheel, if you can't then you have a majhor problem elsewhere but I think you will find that is the problem.
Ken
drivewithken
March 2010