2D Top-Dow Mobile rigibody

im using this code for my 2D TopDown mobile player movement.but when i move player With UI Image buttons player keep moving.it didnt stop.and also player starting of move he is very slow. the he accelerate his speed.how can i fix this.

i add BoxCollider 2D and Rigibody2D my sprite.the set Gravity to 0.

this is my code.

public class PlayerScript : MonoBehaviour {
	public float speed = 150f;
	float hInput ;
	void FixedUpdate()
	{
		Move (hInput);

	}

	public void Move(float horizontalInput){
		if (horizontalInput.Equals(1)) {
						rigidbody2D.AddForce (Vector2.right);
				
		}if (horizontalInput.Equals(2)) {
			rigidbody2D.AddForce (-Vector2.right);
		}if(horizontalInput.Equals(3)) {
			rigidbody2D.AddForce (Vector2.up);
		}
		if(horizontalInput.Equals(4)) {
			rigidbody2D.AddForce (-Vector2.up);
		}
	}

	public void StartMoving(float horizontalInput){
		hInput = horizontalInput;
	}
}
  1. To stop/slowdown your player: increase Drag coefficient on Rigidbody2D.
  2. To move your player faster: when you apply force (rigidbody2D.AddForce) scale vector of force: Vector2.up * speed