My computer does not recognize the import cv2 library

The program should perform facial recognition using Open CV

I already downloaded the library with pip install opencv-python and also tried with pip install opencv-python-headless.

import cv2

face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')

cap = cv2.VideoCapture(0)

while True:
    _, img = cap.read()
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
    faces = face_cascade.detectMultiScale(gray,1.1,4)
    for (x,y,w,h) in faces:
        cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
    cv2.imShow('img',img)
    k = cv2.waitKey(30)
    if k == 27: #27 = ascii ---(space)---
        break

cap.release() #Stop