A disengaged clutch, broken drive belt or internal drive gear failure can prevent the needle from moving.
Engage the hand wheel clutch if you have it disengaged for bobbin winding. If the needle won't move with the clutch engaged, unplug the sewing machine and check the drive belt. Replace the drive belt if it's broken.
If the drive belt is okay, an internal drive gear failure is likely preventing the needle from moving. You'll typically need to have a service technician examine the sewing machine and fix a drive gear failure.
