Dave is right on the mark about the wing being in a full stall. I'd say that about 75% of "radio failures" resulting in crashes are really just stalls which usually turn into a spin. One of the first things that lets you know you are stalling is your controls stop working (there's no air going over them). This lack of control is why most people blame radio failure. The very first thing to do when a stall is coming on is is to push the nose foreward. This is usually against our thinking because the ground is so close. Push the nose foreward anyway! This is the only way to get airspeed and to get air going over the control surfaces.