Python is not responding motion sensor

I am facing some issues with my motion detector sensor in Python. I have looked at this issue in other communities, but the solution did not worked for me. The program opens perfectly without any error, but when it is supposed to show the camera, it shows blank screen. I have followed a YouTube tutorials, but it works for him, and it does not work for me. Can somebody tell me what is wrong with my code? Thank you

YouTube tutorial link: https://www.youtube.com/watch?v=QPjPyUJeY

import threading
import winsound

import cv2
import imutils


cap = cv2.VideoCapture(0, cv2.CAP_DSHOW)

cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)

_, start_frame = cap.read()
start_frame = imutils.resize(start_frame, width=500)
start_frame = cv2.cvtColor(start_frame, cv2.COLOR_BGR2GRAY)
start_frame = cv2.GaussianBlur(start_frame, (21, 21), 0)

alarm = False
alarm_mode = False
alarm_counter = False

def beep_alarm():
    global alarm
    for _ in range(5):
        if not alarm_mode:
            break
        print("Alarm is turning on...")
        winsound.beep(2500, 1000)
    alarm = False



while True:

    _, frame = cap.read()
    frame = imutils.resize(frame, width=500)

    if alarm_mode:
        frame_bw = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
        frame_bw = cv2.GaussianBlur(frame_bw, (5, 5), 0)

        difference = cv2.absdiff(frame_bw, start_frame)
        threshold = cv2.threshold(difference, 25, 255, 
cv2.THRESH_BINARY)[1]
        start_frame = frame_bw

        if threshold.sum() > 300:
            alarm_counter += 1
        else:
            if alarm_counter > 0:
                alarm_counter -= 1

        cv2.imshow("Cam", threshold)
    else:
        cv2.imshow("Cam", frame)

    if alarm_counter > 20:
        if not alarm:
            alarm = True
            threading.Thread(target=beep_alarm).start()

        key_pressed = cv2.waitKey(30)
        if key_pressed == ord("t"):
            alarm_mode = not alarm_mode
            alarm_counter = 0

        if key_pressed == ord("q"):
            alarm_mode = False
            break

cap.release()
cv2.destroyAllWindows()

Image of the errorImage of the issue

Image of the issue

source https://stackoverflow.com/questions/75778633/python-is-not-responding-motion-sensor