im stuck in the sky

i created an old world and i have bulit many things in it everything was fine until i was flying and it seems by mistake i have gone over the wall. then my game became glitchy and i tried what other people said on the internet that i should try walking until i fall but my HUD does not seem to work and i cant move plus my screen has blinking lights i dont know why and i could still see my world but most of it is so glitchy. i tried switching from creative to survival but it didnt work so i switched to creative again but the only thing that was different is the water lives thingy is on my screen and it does not go i think its stuck i also tried using the ender pearl but it didnt work and i keep on seeing a bedrock and then it disappears and not only i see a bedrock i also can see the inside of my houses i dont know what to do. please help me I have spent a lot of time in this world please