After launching the game, I managed to use the Left, Right, Up and Down arrow keys to move the hero character as expected. However, after the first combat with a villain character, the hero character couldn’t move at all in despite of me trying to press any of the arrow keys.

import pygame
import random

class Hero:
    def __init__(self, image_name, position, window):
        self.image = pygame.image.load(image_name).convert_alpha()
        self.image = pygame.transform.scale(self.image, 
                                            (int(self.image.get_width() * 0.5), 
                                             int(self.image.get_height() * 0.5)))
        self.window = window
        self.position = position
        self.rect = self.image.get_rect(center=self.position) 
        self.max_hp = 100
        self.current_hp = self.max_hp
        
    def move(self): 
        adjusted_position = [
            max(self.image.get_width()/2, min(self.window.get_width() - self.image.get_width()/2, self.position[0])),
            max(self.image.get_height()/2 + 20, min(self.window.get_height()-self.image.get_height()/2, self.position[1]))
        ]
        self.position = adjusted_position
        self.rect.center = round(self.position[0]), round(self.position[1])
            
    def draw(self):
        self.window.fill((127, 127, 127))
        self.window.blit(self.image, (self.position[0] - self.image.get_width()/2, self.position[1] - self.image.get_height()/2))

class Villain:
    def __init__(self, image_path, position, window):
        self.image = pygame.image.load(image_path).convert_alpha()
        self.image = pygame.transform.scale(self.image, 
                                            (int(self.image.get_width() * 0.5), 
                                             int(self.image.get_height() * 0.5)))
        self.position = position
        self.window = window
        self.rect = self.image.get_rect(center=self.position)  
        self.max_hp = 100
        self.current_hp = self.max_hp
        
    def move(self, x_range=(-10, 10), y_range=(-10, 10)):
        self.position[0] += random.randint(*x_range)  
        self.position[1] += random.randint(*y_range)  
        adjusted_position = [
            max(self.image.get_width()/2, min(self.window.get_width() - self.image.get_width()/2, self.position[0])),
            max(self.image.get_height()/2 + 10, min(self.window.get_height() - self.image.get_height()/2, self.position[1]))
        ] 
        self.position = adjusted_position
        self.rect.center = round(self.position[0]), round(self.position[1])
    
    def draw(self):
        self.window.blit(self.image, (self.position[0] - self.image.get_width()/2, self.position[1] - self.image.get_height()/2))
        
class Scene:
    def __init__(self, window):
        self.window = window
        self.hero = Hero('hero.png', [400, 300], self.window)
        self.villains = [Villain('villain.png', [80, 80], self.window),
                         Villain('villain.png', [720, 80], self.window),
                         Villain('villain.png', [80, 520], self.window),
                         Villain('villain.png', [720, 520], self.window)]
        self.current_villain = None
        self.in_combat = False
        
    def check_for_combat(self):
        for villain in self.villains:
            if pygame.math.Vector2(villain.position).distance_to(self.hero.position) < 50:
                self.in_combat = True
                self.current_villain = villain
                return True
        return False
        
    def handle_combat(self): 
            if self.in_combat and self.current_villain:  
                hero_damage = int(input('Enter a number between 0 and 8: '))
                self.current_villain.current_hp -= hero_damage
                if self.current_villain.current_hp <= 0:
                    print("Enemy defeated!")
                    self.villains.remove(self.current_villain)
                    self.in_combat = False
                    self.current_villain = None    
                else:
                    enemy_damage = random.randint(2, 8)
                    self.hero.current_hp -= enemy_damage
                if self.hero.current_hp <= 0:
                    print("Hero fell!")
                    
    def handle_events(self):
        keys = pygame.key.get_pressed()
        move_speed = 2
        if keys[pygame.K_LEFT]:
            self.hero.position[0] -= move_speed
        if keys[pygame.K_RIGHT]:
            self.hero.position[0] += move_speed
        if keys[pygame.K_UP]:
            self.hero.position[1] -= move_speed
        if keys[pygame.K_DOWN]:
            self.hero.position[1] += move_speed
        print(self.hero.position)
        self.hero.move()
        for villain in self.villains:
            villain.move()
        if not self.in_combat:
            if self.check_for_combat():
                return
                
    def draw(self):
        self.window.fill((127, 127, 127))
        self.window.blit(self.hero.image, self.hero.position)
        for villain in self.villains:
            villain.draw()
        pygame.display.update()

class Game:
    def __init__(self):
        pygame.init()
        self.window = pygame.display.set_mode((800, 600))
        self.game_scene = Scene(self.window)
        
    def run(self):
        while True:
            for event in pygame.event.get(): 
                if event.type == pygame.QUIT:  
                    pygame.quit() 
                     
            self.game_scene.handle_events() 
            self.game_scene.handle_combat()
            self.game_scene.draw()

window = pygame.display.set_mode((800, 600))            
game = Game()
game.run() 

My question is: what caused the hero character stop moving after the first encounter? How can I fix it?