I'm trying to help you by giving a resume of steps you need to do to make your virtual host working. Make your own changes to adapt it with your project (name, location...etc)
I suppose that you have a running website which you can access it using http://127.0.0.1/example.com
I suppose that you want to create a virtual host to access it using http://example.dev
I suppose that the folder "example.com" is under "/var/www/"
I suppose that you are working on Ubuntu (or using a Windows 10 Ubuntu Bash)
Step 1
sudo nano etc/apache2/sites-available/example.com.conf
Copy/paste the following content inside it:
<VirtualHost *:80>
ServerName www.example.dev
ServerAlias example.dev
ServerAdmin changeThisWithYourEmail
DocumentRoot /var/www/example.com/
DirectoryIndex index.php
<Directory "/var/www/dev">
Options Multiviews FollowSymLinks
MultiviewsMatch Any
AllowOverride All
Order allow,deny
Allow from all
</Directory>
ErrorLog ${APACHE_LOG_DIR}/example_error.log
CustomLog ${APACHE_LOG_DIR}/example_access.log combined
</VirtualHost>
Step 2
sudo a2ensite example.com.conf
Step 3
sudo nano /etc/hosts
and then add this line at the end of the file:
127.0.1.1 example.dev
Step 4
sudo service apache2 restart
Step 5
Check if http://example.dev is showing the same result as http://example.com