Save last rotation or the camera and apply it after end of event.

In my game I have to cameras, and when I switch to the "2d" one ( player.is2D) I want the 3d camera to go back to the x rotation axis it had before: here's my code :

 using UnityEngine;
 using System.Collections;
 public class rotation : MonoBehaviour {
 
     [Range(1f, 10f)]
     public float Sensitivity;
     
     public float Rotation_Smoothness; //Believe it or not, adjusting this before anything else is the best way to go.
     public float Resulting_Value_from_Input_x;
     public float Resulting_Value_from_Input_y;
     private Quaternion Quaternion_Rotate_From;
     private Quaternion Quaternion_Rotate_To_x;
     private Quaternion Quaternion_Rotate_To_y;
     public GameObject pivot;
     switchdimension player;
     
 
     // Use this for initialization 
     public void Start()
     {
         player = GetComponent<switchdimension>();
     }
     public void Set (float sensi) {
         Sensitivity = sensi;
         Debug.Log(Sensitivity);
     }
     void Update () {
         if (FindObjectOfType<PauseMenu>().InvertYAxis == false)
         {
             Resulting_Value_from_Input_x += Input.GetAxis("Mouse X") * Sensitivity * 100 * Time.deltaTime + Input.GetAxis("HorizontalCam") * Sensitivity * 100 * Time.deltaTime; ;
             Resulting_Value_from_Input_y += Input.GetAxis("Mouse Y") * Sensitivity * 50 * Time.deltaTime + Input.GetAxis("VerticalCam") * Sensitivity * 50 * Time.deltaTime; ;
         } else
         {
             Resulting_Value_from_Input_x += Input.GetAxis("Mouse X") * Sensitivity * 100 * Time.deltaTime + Input.GetAxis("HorizontalCam") * Sensitivity * 100 * Time.deltaTime; ;
             Resulting_Value_from_Input_y -= Input.GetAxis("Mouse Y") * Sensitivity * 50 * Time.deltaTime + Input.GetAxis("VerticalCam") * Sensitivity * 50 * Time.deltaTime;
         
         }
         Quaternion_Rotate_To_y = Quaternion.Euler(Mathf.Clamp(Resulting_Value_from_Input_y, -70, 80), transform.rotation.y, 0);
         Resulting_Value_from_Input_y = Mathf.Clamp(Resulting_Value_from_Input_y, -40, 70);
         Quaternion_Rotate_From = transform.rotation;
         Quaternion_Rotate_To_x = Quaternion.Euler (0,Resulting_Value_from_Input_x,0);
         transform.rotation = Quaternion.Lerp (Quaternion_Rotate_From, Quaternion_Rotate_To_x, Time.deltaTime*Rotation_Smoothness);
         pivot.transform.localRotation = Quaternion.Lerp(pivot.transform.localRotation, Quaternion_Rotate_To_y, Time.deltaTime * Rotation_Smoothness);
     }
 
 }