Why Trail Renderer and A Basic Script Stops Working?

Hi, Sometimes in my game trail renderer of specific object and a specific script stops working at the same time without a reason. Object is my player's bullets, contains a Rigidbody2D, Box Collider (as trigger) and two scripts. Scripts are:

 using UnityEngine;
 using System.Collections;
 
 public class PlayerBullet : MonoBehaviour {
 
     Transform player;
 
     void Awake() {
 
         player = GameObject.FindGameObjectWithTag ("Player").GetComponent<Transform>();
 
     }
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
         if (Vector3.Distance (player.position, transform.position) > 10) {
 
             Destroy (gameObject);
 
         }
     }
 
     void OnTriggerEnter2D(Collider2D other) {
 
         if (other.tag == "Player" || other.tag == "PlayerBullet" || other.tag.Contains ("Pickup") ||
             other.tag == "Explosion") {
             return;
         } else if (other.tag == "ProtoZero") {
 
             other.GetComponent<ProtoZero> ().damageMe (10);
             Destroy (gameObject);
 
         } else if (other.tag == "ProtoOne") {
 
             other.GetComponent<ProtoOne> ().damageMe (10);
             Destroy (gameObject);
 
         } else if (other.tag == "ProtoTwo") {
 
             other.GetComponent<ProtoTwo> ().damageMe (10);
             Destroy (gameObject);
 
         } else {
             Destroy (gameObject);
         }
 
     }
 
 }
 

and

 using UnityEngine;
 using System.Collections;
 
 public class BulletDestroy : MonoBehaviour {
 
     public Transform explosion;
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
     
     }
 
     void OnDestroy() {
         Transform newExplo = Instantiate (explosion);
         newExplo.position = transform.position;
 
         Destroy (newExplo.gameObject, 1f);
     }
 }
 

That simple script stops working also:

 using UnityEngine;
 using System.Collections;
 
 public class PickupShake : MonoBehaviour {
 
     int direction = 1;
     float firstY;
 
     // Use this for initialization
     void Start () {
     
         firstY = transform.position.y;
 
     }
     
     // Update is called once per frame
     void Update () {
     
         if (Mathf.Abs (transform.position.y - firstY) >= 0.05f)
             direction *= -1;
         
         transform.position += new Vector3 (0, direction * 0.2f * Time.deltaTime, 0);
 
     }
 }
 

I can't figure out what is the problem. Thanks for your help in advance!