Move character using Camera Input

I would have to look at what you're doing to find your character in order to find out what the problem is... But putting this on your camera should work. (Make sure your character is tagged as "Player" for this script to work. I usually use tags to find my game objects)

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class CameraScript : MonoBehaviour
 {
     float movementSpeed = 3.0f;
     GameObject player;
 
     // Use this for initialization
     void Start()
     {
         player = GameObject.FindGameObjectWithTag("Player");
     }
 
     // Update is called once per frame
     void Update()
     {
         // If we press/hold W
         if (Input.GetKey(KeyCode.W))
         {
             // Move the player Forwards
             player.transform.Translate(Vector3.forward * movementSpeed * Time.deltaTime);
         }
         // Or if we press/hold S
         else if (Input.GetKey(KeyCode.S))
         {
             // Move the player Backwards
             player.transform.Translate(Vector3.back * movementSpeed * Time.deltaTime);
         }
 
         // If we press/hold A
         if (Input.GetKey(KeyCode.A))
         {
             // Strafe the player left
             player.transform.Translate(Vector3.left * movementSpeed * Time.deltaTime);
         }
         // Or if we press/hold D
         else if (Input.GetKey(KeyCode.D))
         {
             // Strafe the player right
             player.transform.Translate(Vector3.right * movementSpeed * Time.deltaTime);
         }
     }
 }

Note: This script makes it so you can't press W and S at the same time, same with A and D. If you want to change this then change the "else if"s to "if"s.
The only difference will be that holding A and D or W and S will make your player stay still since you're telling the player to move opposite directions at the same time.

I hope this works for you! :)

This works perfect !! Thanks!