my zig zag sewing machine is locked up?

i have a zig zag sewing machine model 146-b i have the manual and all the attatchments that go to it but the problem is it is locked up. i can't get it to work at all i used ti once and it has been locked up since then. the light will come on and i hear a noise but it still won't do anything. ive tried everything to get it unlocked. how do i fix this problem