Moving Player Up and Down in 2D

Questions & Answers
1

First off here is the code for side to side:

pragma strict

var health : int = 100; 
var speed : int = 400;

function Start () {
}

function Update () { 
    if(Input.GetAxis("Horizontal")){     
        transform.Translate(Vector3(Input.GetAxis("Horizontal") * speed * Time.deltaTime, 0, 0)); 
    } 
}

What I want to add is my player being able to move up and down on the Y axis. I have done things like this:

pragma strict
var health : int = 100; 
var speed : int = 400;

function Start () {
}

function Update () { 
    if(Input.GetAxis("Horizontal")){ 
        transform.Translate(Vector3(Input.GetAxis("Horizontal") * speed * Time.deltaTime, 0, 0)); 
    }
    if(Input.GetAxis("Vertical")){ 
        transform.Translate(Vector3(Input.GetAxis("Vertical") * speed * Time.deltaTime, 0, 0));
    }
}

But then it just makes it so when I press W to go up it just moves left, and when I press S to go down it just makes me go right. Then when I try to go side to side on the X axis using A and D it does nothing. The camera angle is like PacMan, so the camera is directly above the seen looking down on the terrain. I used Javacode for the scripts and my main character was built off of a cube.
It is a 2D game.

2

it should be:

function Update () 
{ 
if(Input.GetAxis("Horizontal"))
            { 
               transform.Translate(Vector3(Input.GetAxis("Horizontal") * speed * Time.deltaTime, 0, 0));
            }
            if(Input.GetAxis("Vertical"))
            {
                transform.Translate(Vector3(0, Input.GetAxis("Vertical") * speed * Time.deltaTime, 0));
            }

}