Add item to GUI inventory and drop him back in the scene with keys

Hello, I'm trying to make an inventory system for 2D top down game. I would like to pick up objects with a key and store it into my inventory. I should be able to see what items I have in my inventory and be able to drop them back in the scene with a key. I'm stack and have no idea what to do :confused:. Any help would be grateful. This is my code for the inventory:

 public class Inventory : MonoBehaviour {
  
     public GameObject[] inventory = new GameObject[10];
  
     public void addItem (GameObject item)
     {
         bool itemAdded = false;
         //find the first open slot in the inventory
         for (int i = 0; i < inventory.Length; i++)
         {
             if(inventory [i] == null)
             {
                 inventory[i] = item;
                 Debug.Log(item.name  + " " + "was added");
                 itemAdded = true;
                 break;
             }
         }
         //inventory full
         if (!itemAdded)
         {
             Debug.Log("Inventory full!");
         }
     }
  
     public GameObject FindItemByType(string itemType)
     {
         for (int i = 0; i< inventory.Length; i++)
         {
             if(inventory[i] != null)
             {
                 if(inventory[i].GetComponent<IntercationObject> ().itemType == itemType)
                 {
                     //we found the type of item we wanted
                     return inventory[i];
                 }
             }
         }
         //item not found
         return null;
     }
  
     public void removeItem (GameObject item)
     {
         for(int i = 0; i<inventory.Length; i++)
         {
             if(inventory[i] == item)
                 //remove founded item
             {
                 inventory[i] = null;
                 Debug.Log(item.name + "was removed from the inventory");
                 break;
  
             }
         }
     }
 }

This is my code for the interaction with the object:

 public class IntercationObject : MonoBehaviour {
  
     public bool inventory; // if true this item can be stored
     public string itemType; //this will tell what type of object it is
  
     public void DoInteraction()
  
     {
         //Picked and put into inventory
         gameObject.SetActive(false);
     }
 }

This is my code for the interaction with the player:

 public class PlayerInteraction : MonoBehaviour
 {
  
     public GameObject currentInterObj = null;
     public IntercationObject currentInterObjScript = null;
     public Inventory inventory;
  
      void Update()
     {
         if (Input.GetButtonDown("Interact") && currentInterObj)
         {
             if (currentInterObjScript.inventory)
             {
                 inventory.addItem(currentInterObj);
             }
             // Do something with the object
             currentInterObj.SendMessage("DoInteraction");
         }
  
         //Use item from inventory
         if (Input.GetButtonDown("Use item"))
         {
             //Check the inventory for an item
             GameObject Kost = inventory.FindItemByType("Bone");
             Debug.Log("nešto");
          
         }
  
     }
  
  
     private void OnTriggerEnter2D(Collider2D other)
     {
         if (other.CompareTag("interObject"))
         {
             Debug.Log(other.name);
             currentInterObj = other.gameObject;
             currentInterObjScript = currentInterObj.GetComponent<IntercationObject>();
         }
     }
     private void OnTriggerExit2D(Collider2D other)
     {
         if (other.CompareTag("interObject"))
         {
             if (other.gameObject == currentInterObj)
             {
                 currentInterObj = null;
             }
  
         }
     }
 }

And this is my code for the GUI inventory:

 public class GUIInventory : MonoBehaviour {
     private bool inventoryWindowToggle = false;
     private Rect inventoryWindowRect = new Rect(300, 100, 400, 400);
    
  
     // Use this for initialization
     void Start () {
        
     }
    
     // Update is called once per frame
     void Update () {
         if(Input.GetButtonDown("ShowHideInventory"))
         {
             inventoryWindowToggle = !inventoryWindowToggle;
         }
        
     }
  
      void OnGUI()
     {
         inventoryWindowToggle = GUI.Toggle(new Rect(0, 0, 0, 0), inventoryWindowToggle, "inventory");
         if (inventoryWindowToggle)
         {
             inventoryWindowRect = GUI.Window(0, inventoryWindowRect, inventoryWindowMethod, "inventory");
         }
     }
  
     void inventoryWindowMethod(int WindowId)
     {
         GUILayout.BeginHorizontal();
         GUILayout.Button("Item 1", GUILayout.Height(50));
         GUILayout.Button("Item 2", GUILayout.Height(50));
         GUILayout.Button("Item 3", GUILayout.Height(50));
         GUILayout.EndHorizontal();
  
         GUILayout.BeginHorizontal();
         GUILayout.Button("Item 4", GUILayout.Height(50));
         GUILayout.Button("Item 5", GUILayout.Height(50));
         GUILayout.Button("Item 6", GUILayout.Height(50));
         GUILayout.EndHorizontal();
  
         GUILayout.BeginHorizontal();
         GUILayout.Button("Item 7", GUILayout.Height(50));
         GUILayout.Button("Item 8", GUILayout.Height(50));
         GUILayout.Button("Item 9", GUILayout.Height(50));
         GUILayout.EndHorizontal();
  
         GUILayout.BeginHorizontal();
         GUILayout.Button("Item 10", GUILayout.Height(50));
         GUILayout.EndHorizontal();
  
     }
  
 }