Login to the database (MySql) where the Drupal 7 is installed. Then run the following query on your database;
Update users set name='test@example.com', pass='$S$DD7aCRCy6iTddzIbeTPIVdwg4Ea9KgFqpSXZpGjMQtWBA8zzg24t' where uid=1;
Now login Drupal via the user with Username: test@example.com, Password: 123456