My main character isn't being able to colide with the objects.

 using UnityEngine;
 using System.Collections;
 
 public class PlayerController : MonoBehaviour {
 
     public float movespeed;
     public float jumpheight;
 
     public Transform Groundcheck;
     public float GroundcheckRadius;
     public LayerMask WhatIsGround;
     private bool grounded;
 
     private bool doubleJump;
 
     private Animator anim;
 
     // Use this for initialization
     void Start() {
         anim = GetComponent<Animator>();
     }
 
     void FixedUpdate()
     {
         grounded = Physics2D.OverlapCircle(Groundcheck.position, GroundcheckRadius, WhatIsGround);
     }
 
     // Update is called once per frame
     void Update() {
 
         if (grounded)
             doubleJump = false;
 
         if (Input.GetKeyDown(KeyCode.W) && grounded)
         {
             //GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, jumpheight);
             salto();
         }
 
         if (Input.GetKeyDown(KeyCode.W) && !doubleJump && !grounded)
         {
             //GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, jumpheight);
             salto();
             doubleJump = true;
         }
 
         if (Input.GetKey(KeyCode.D))
         {
             GetComponent<Rigidbody2D>().velocity = new Vector2(movespeed, GetComponent<Rigidbody2D>().velocity.y);
         }
 
         if (Input.GetKey(KeyCode.A))
         {
             GetComponent<Rigidbody2D>().velocity = new Vector2(-movespeed, GetComponent<Rigidbody2D>().velocity.y);
         }
 
         anim.SetFloat("Speed",Mathf.Abs (GetComponent < Rigidbody2D>().velocity.x));
 
     }
 
     public void salto()
         {
       GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, jumpheight);
         }
 }
 

So this is main character code. I will show aswell the Script that i use to when i collide with spikes he dies.

 using UnityEngine;
 using System.Collections;
 
 public class KillPlayer : MonoBehaviour
 {
 
     public LevelManager levelManager;
 
     // Use this for initialization
     void Start()
     {
 
         levelManager = FindObjectOfType<LevelManager>();
 
     }
 
     // Update is called once per frame
     void Update()
     {
 
     }
 
     void OnTriggerEnter2D(Collider2D other)
     {
         if (other.name == "Kappa kek")
         {
             levelManager.RespawnPlayer();
         }
     }
 }

This was all working until i tried to place the respawn particles and death particles working out. Since i placed this code the Colision isn't working, the Player passes right in the middle of the object nothing happens. And before i placed this code with the particles everything was fine...

 using UnityEngine;
 using System.Collections;
 
 public class LevelManager : MonoBehaviour
 {
 
     public GameObject currentCheckpoint;
 
     private PlayerController player;
 
     public GameObject deathParticle;
     public GameObject respawnParticle;
 
     public float respawnDelay;
 
     // Use this for initialization
     void Start()
     {
         player = FindObjectOfType<PlayerController>();
     }
 
     // Update is called once per frame
     void Update(){
 
     }
 
     public IEnumerator RespawnPlayer()
     {
         Instantiate(deathParticle, player.transform.position, player.transform.rotation);
         player.enabled = false;
         player.GetComponent<Renderer>().enabled = false;
         Debug.Log("Player Respawn");
         yield return new WaitForSeconds(respawnDelay);
         player.transform.position = currentCheckpoint.transform.position;
         player.enabled = true;
         player.GetComponent<Renderer>().enabled = true;
         Instantiate(respawnParticle, currentCheckpoint.transform.position, currentCheckpoint.transform.rotation);
     }
 
     public void RespawnPlayerCo()
     {
         StartCoroutine("RespawnPlayerCo");
     }
 }