Help this script doesnt work

Unity Engine
1

if (Input.GetKeyDown(KeyCode.Space) && isFalling == false)
(
rigidbody.velocity.y = jumpHeight;
isFalling = true;
)
)

functionOnCollisionStay ()
{
isFalling = false;
}

2

I think you are using parantheses where you should be using brackets, and then have an additional paren beyond that.

Try:

if (...)
{
  rigidbody...
  isFalling...
}