When you say you appear in blueness and clouds do you mean that there is no ground at all? It's possible your camera has moved out of the map boundary. Look at the heightmap in the top left corner, is the pointer arrow there? Does it look like this?

Click an area of the heightmap image while still in the Map Maker menu until it appears again:

If there still is no visible ground your camera may have zoomed out quite a bit. Look straight down and hold the
W button until the ground is visible. You can press the
= and
- button on your keyboard to change the camera speed.