Making a simple 2-D Jump script

I can not believe how difficult it has been for me to create a jump script. I have spent around 6 hours today looking through various threads on this forum, yet to no avail. Every implementation seems to get me the same results, I can jump infinitely with varying heights... I am a beginner to C# and I would greatly appreciate if you guys could help me a little bit.

 using UnityEngine;
 using System.Collections;
 
 public class PlayerScript : MonoBehaviour {
 
     // Use this for initialization
     public enum State{
         normal,
         jumping
     }
     public State state;
 
 
     public bool canJump = true;
     public float j;
 
     
     
     // Update is called once per frame
     void Update() {
          
      
 
                 float inputX = Input.GetAxis ("Horizontal");
                 float inputY = Input.GetAxis ("Vertical");
 
                  
                 
             if (Input.GetButtonDown ("Jump")) Jump();
             Vector2 speed = new Vector2(25,25);
             Vector3 movement = new Vector3(speed.x * inputX, speed.y * inputY, 0);
             j = Input.GetAxis ("Jump");
 
         Vector4 jumping = new Vector4 (0,speed.y * j, 0);
 
         movement *= Time.deltaTime;
         transform.Translate (movement);
 
         transform.Translate(jumping);
         jumping *= Time.deltaTime; 
 
     }
 
 
 }

This is my code prior to me trying, unsuccessfully, to get my character to jump. :P