.htaccess doesn't work in apache

Question

I have the following problem:

I want to remove .php and .html extention from url of my website.

The URL is localhost/MySiteDir/MySitePage.php and I want to obtain localhost/MySiteDir/MySitePage.

I am following this:

https://alexcican.com/post/how-to-remove-php-html-htm-extensions-with-htaccess/

& this

How to remove file extension from website address? guides.

So I created a .htaccess file on my MySiteDir and I put this code on this file:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\.]+)$ $1.php [NC,L]

But it doesn't work.

I have changed etc/apache2/sites-enabled/000-default.conf file adding

<Directory /var/www/html>
            Options Indexes FollowSymLinks MultiViews
            AllowOverride All
            Order allow,deny
            allow from all
  </Directory>

in this way:

<VirtualHost *:80>



<Directory /var/www/html>
            Options Indexes FollowSymLinks MultiViews
            AllowOverride All
            Order allow,deny
            allow from all
  </Directory>

    # The ServerName directive sets the request scheme, hostname and port that
    # the server uses to identify itself. This is used when creating
    # redirection URLs. In the context of virtual hosts, the ServerName
    # specifies what hostname must appear in the request's Host: header to
    # match this virtual host. For the default virtual host (this file) this
    # value is not decisive as it is used as a last resort host regardless.
    # However, you must set it for any further virtual host explicitly.
    #ServerName www.example.com

    ServerAdmin webmaster@localhost
    DocumentRoot /var/www/html

    # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
    # error, crit, alert, emerg.
    # It is also possible to configure the loglevel for particular
    # modules, e.g.
    #LogLevel info ssl:warn

    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    # For most configuration files from conf-available/, which are
    # enabled or disabled at a global level, it is possible to
    # include a line for only one particular virtual host. For example the
    # following line enables the CGI configuration for this host only
    # after it has been globally disabled with "a2disconf".
    #Include conf-available/serve-cgi-bin.conf


</VirtualHost>

# vim: syntax=apache ts=4 sw=4 sts=4 sr noet

and in my .htaccess file I put:

 RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php [L]

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.html -f
RewriteRule ^(.*)$ $1.html [L]

when I try to access my website I receive a 404 Error.