C＃逻辑代码不起作用

由于我的代码，我真的需要帮助。让我解释一下......我想制作一种马里奥游戏，我做了所有的事情，如添加箭头使角色移动，添加马里奥角色，添加一个地面，我正在努力马里奥将跳跃的块。那个
愚蠢地不工作，这是古怪的，因为地面工作但不是我让你看到的块。我知道有一些代码没用，但生病后删除它们。

I really need help, because of my code. Let me explain... I want to make a kind of Mario Game and I did all the stuff like add arrows to make the character move , add the mario character , add a ground and I am working on a block that mario will jump. that stupidly dont work, it is bizzare because the ground is working but not the block I let you see just under. I know there is some codes that is useless, but ill remove them after.

因此它位于  私有空间引力（）

So it is in the section of  private void gravity()

PS - I我12岁，请不要给我一个100k的代码

PS - I am 12 years old pls dont give me a code of 100k