Help i get this error Assets/MouseManager.cs(11,20): error CS1525: Unexpected symbol `{'

I'm not sure where was your original problem as t$$anonymous$$s script had soo many error. You should declare Vector2 mousePos2D outside the if() otherwise you can't use its value in the Raycast. You were missing a couple of " ; " "$$anonymous$$t !=null" always returns true use "$$anonymous$$t" instead

 using UnityEngine; 
 using System.Collections;
 
 public class MouseManager : MonoBehaviour {
 
     Vector2 mousePos2D;
 
     void Update() {
         if( Input.GetMouseButtonDown (0)){
             Vector3 mouseWorldPos3D = Camera.main.ScreenToWorldPoint(Input.mousePosition);
             mousePos2D = new Vector2(mouseWorldPos3D.x, mouseWorldPos3D.y);
         }
         
         Vector2 dir = Vector2.zero;
         RaycastHit2D $$anonymous$$t = Physics2D.Raycast (mousePos2D, dir);
         if($$anonymous$$t && $$anonymous$$t.collider && $$anonymous$$t.collider.GetComponent<Rigidbody2D>() != null) {
             $$anonymous$$t.collider.GetComponent<Rigidbody2D>().gravityScale = 1;
         }
     }
 }