<<<< Q.

1. How to disable pause() in game_loop() once game_over() function is called?
2. And why does the bullet keep re-appearing even after I have changed the bullet_state to 'ready' in function game_over()?

def game_loop(): global playerX, playerY, playerX_change, playerY_change, bulletX, bulletY, bulletY_change, bullet_state global score

# background music
mixer.music.load('bg music.mp3')
mixer.music.play(-1)

running = True

while running:

    # set background image(bg)
    bg = pygame.image.load('bg 2.PNG')
    screen.blit(bg, (0, 0))

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                running = False
            if event.key == pygame.K_p:
                pause()
                game_loop()

        # movement of player L, R , U & D
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                playerX_change -= 7

            if event.key == pygame.K_RIGHT:
                playerX_change += 7

            if event.key == pygame.K_UP:
                playerY_change -= 7

            if event.key == pygame.K_DOWN:
                playerY_change += 7

            # update bullet position when shift in player position + bullet sound
            if event.key == pygame.K_SPACE:
                if bullet_state == "ready":
                    bullet_sound = mixer.Sound('bullet.wav')
                    bullet_sound.play()
                    bulletX = playerX
                    fire_bullet(bulletX, bulletY)

        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                playerX_change = 0

            if event.key == pygame.K_UP or event.key == pygame.K_DOWN:
                playerY_change = 0

    playerX += playerX_change
    # for player stay inside game window (L & R)
    if playerX >= 650:  # R
        playerX = 650
    elif playerX <= 20:  # L
        playerX = 20

    playerY += playerY_change
    # for player stay inside game window (U & D)
    if playerY >= 370:  # D
        playerY = 370
    if playerY <= 350:  # U
        playerY = 350

    # for enemies to stay inside game window & enemies movement
    for i in range(no_of_enemies):
        # game over
        if enemyY[i] >= 340:
            for j in range(no_of_enemies):
                enemyY[j] = 1000
            game_over()
            break

        enemyX[i] += enemyX_change[i]
        if enemyX[i] >= 720:  # R
            enemyX_change[i] -= 5
            enemyY[i] += enemyY_change[i]
        elif enemyX[i] <= 20:  # L
            enemyX_change[i] += 5
            enemyY[i] += enemyY_change[i]

        # collision for every enemy
        result = collision(enemyX[i], enemyY[i], bulletX, bulletY)
        if result:
            enemy_to_blast(enemyX[i], enemyY[i])
            explosion_sound = mixer.Sound('explosion.wav')
            explosion_sound.play()
            score += 1
            bulletY = 445
            bullet_state = "ready"
            enemyX[i] = random.randint(20, 720)
            enemyY[i] = random.randint(20, 150)

        # call enemy func
        enemy(enemyX[i], enemyY[i], i)

    # bullet movement
    if bullet_state == "fire":
        fire_bullet(bulletX, bulletY)
        bulletY -= bulletY_change
        # re-appearance of bullet at start point
        if bulletY <= 0:  # U
            bulletY = 445
            bullet_state = "ready"

    # call funcs 'player' & 'score'
    player(playerX, playerY)
    display_score()
    display_pause()

    pygame.display.update()

def pause(): global running

# background music for paused screen
mixer.music.load('start.mp3')
mixer.music.play(-1)

paused = True

while paused:

    txt_on_screen(paused_text_font_1, "PROJECT ANNIHILATION", 0, (-120), white, black)
    txt_on_screen(paused_text_font_2, "0N HOLD", 0, (-70), red, black)
    txt_on_screen(paused_text_font_3, " RESUME >> esc ", 0, 0, black, light_purple)
    txt_on_screen(start_text_font_3, " SETTINGS >> s ", 0, 50, black, light_purple)
    txt_on_screen(start_text_font_4, " QUIT >> Delete ", 0, 100, black, light_purple)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            paused, running = False
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:  # RESUME GAME
                paused = False
                mixer.music.stop()
                break
            if event.key == pygame.K_DELETE:
                paused, running = False
            # if event.type == pygame.K_s >>>>> volume settings
    pygame.display.update()

def game_over(): global bullet_state # centering game-over text txt_on_screen(game_over_font, "GAME-OVER!", 0, 0, light_purple, None) # centering game-over 'instructions' text txt_on_screen(below_txt_font, "Press 'Delete' to QUIT, 'r' to RESTART", 0, 50, white, black)

# game-over sound effect
end_sound = mixer.Sound('end.wav')
end_sound.play()
mixer.music.set_volume(0)

# unable shooting bullets
for event in pygame.event.get():
    if event.type == pygame.KEYDOWN:
        if event.key == pygame.K_SPACE:
            bullet_state = "ready"
        if event.key == pygame.K_r:
            game_loop()

How can I disable pause() in game_loop() once game_over() function is called?

def game_loop():
    global playerX, playerY, playerX_change, playerY_change, bulletX, bulletY, bulletY_change, bullet_state
    global score

    # background music
    mixer.music.load('bg music.mp3')
    mixer.music.play(-1)

    running = True

    while running:

        # set background image(bg)
        bg = pygame.image.load('bg 2.PNG')
        screen.blit(bg, (0, 0))

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                running = False
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    running = False
                if event.key == pygame.K_p:
                    pause()
                    game_loop()

            # movement of player L, R , U & D
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    playerX_change -= 7

                if event.key == pygame.K_RIGHT:
                    playerX_change += 7

                if event.key == pygame.K_UP:
                    playerY_change -= 7

                if event.key == pygame.K_DOWN:
                    playerY_change += 7

                # update bullet position when shift in player position + bullet sound
                if event.key == pygame.K_SPACE:
                    if bullet_state == "ready":
                        bullet_sound = mixer.Sound('bullet.wav')
                        bullet_sound.play()
                        bulletX = playerX
                        fire_bullet(bulletX, bulletY)

            if event.type == pygame.KEYUP:
                if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                    playerX_change = 0

                if event.key == pygame.K_UP or event.key == pygame.K_DOWN:
                    playerY_change = 0

        playerX += playerX_change
        # for player stay inside game window (L & R)
        if playerX >= 650:  # R
            playerX = 650
        elif playerX <= 20:  # L
            playerX = 20

        playerY += playerY_change
        # for player stay inside game window (U & D)
        if playerY >= 370:  # D
            playerY = 370
        if playerY <= 350:  # U
            playerY = 350

        # for enemies to stay inside game window & enemies movement
        for i in range(no_of_enemies):
            # game over
            if enemyY[i] >= 340:
                for j in range(no_of_enemies):
                    enemyY[j] = 1000
                game_over()
                break

            enemyX[i] += enemyX_change[i]
            if enemyX[i] >= 720:  # R
                enemyX_change[i] -= 5
                enemyY[i] += enemyY_change[i]
            elif enemyX[i] <= 20:  # L
                enemyX_change[i] += 5
                enemyY[i] += enemyY_change[i]

            # collision for every enemy
            result = collision(enemyX[i], enemyY[i], bulletX, bulletY)
            if result:
                enemy_to_blast(enemyX[i], enemyY[i])
                explosion_sound = mixer.Sound('explosion.wav')
                explosion_sound.play()
                score += 1
                bulletY = 445
                bullet_state = "ready"
                enemyX[i] = random.randint(20, 720)
                enemyY[i] = random.randint(20, 150)

            # call enemy func
            enemy(enemyX[i], enemyY[i], i)

        # bullet movement
        if bullet_state == "fire":
            fire_bullet(bulletX, bulletY)
            bulletY -= bulletY_change
            # re-appearance of bullet at start point
            if bulletY <= 0:  # U
                bulletY = 445
                bullet_state = "ready"

        # call funcs 'player' & 'score'
        player(playerX, playerY)
        display_score()
        display_pause()

        pygame.display.update()

def pause():
    global running

    # background music for paused screen
    mixer.music.load('start.mp3')
    mixer.music.play(-1)

    paused = True

    while paused:

        txt_on_screen(paused_text_font_1, "PROJECT ANNIHILATION", 0, (-120), white, black)
        txt_on_screen(paused_text_font_2, "0N HOLD", 0, (-70), red, black)
        txt_on_screen(paused_text_font_3, " RESUME >> esc ", 0, 0, black, light_purple)
        txt_on_screen(start_text_font_3, " SETTINGS >> s ", 0, 50, black, light_purple)
        txt_on_screen(start_text_font_4, " QUIT >> Delete ", 0, 100, black, light_purple)

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                paused, running = False
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:  # RESUME GAME
                    paused = False
                    mixer.music.stop()
                    break
                if event.key == pygame.K_DELETE:
                    paused, running = False
                # if event.type == pygame.K_s >>>>> volume settings
        pygame.display.update()

def game_over():
    global bullet_state
    # centering game-over text
    txt_on_screen(game_over_font, "GAME-OVER!", 0, 0, light_purple, None)
    # centering game-over 'instructions' text
    txt_on_screen(below_txt_font, "Press 'Delete' to QUIT, 'r' to RESTART", 0, 50, white, black)

    # game-over sound effect
    end_sound = mixer.Sound('end.wav')
    end_sound.play()
    mixer.music.set_volume(0)

    # unable shooting bullets
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_SPACE:
                bullet_state = "ready"
            if event.key == pygame.K_r:
                game_loop()