How to fix this minecraft glitch?

I was flying to the edge of my world that I worked really hard on and I was holding onto the forward button with fly mode then when I let go and look down I don't see my world and I thought that I just was too high in the air so I released the fly mode and then I heard the ground sound but I was still in the sky and I jumped but I was still in the sky so I flew up and went down but I stopped in the sky so please let me know how to fix this glitch