RECOVER MYSQL. IF MYSQL COULD NOT BE STARTED

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1)The MySQL database is configured to use InnoDB engine by default. 

You can add the innodb_force_recovery=1 option in the main MySQL configuration file at /opt/bitnami/mysql/etc/my.cnf to try and fix the database:

                [mysqld]
          innodb_force_recovery = 1

2) Start the MySQL database with the following command:

 mysqld --skip-grant-tables --user=mysql --skip-external-locking --port=3306 --sock=/opt/bitnami/mysql/tmp/mysql.sock

3)mysql -u root -p

4)o not forget to remove the innodb_force_recovery option from the my.cnf file and restart the MySQL server again  

5)If they show any permission issue use

 sudo chown mysql:root -R /opt/bitnami/mysql/data chmod 1777 /tmp  

To find error logs:

 cd /var/log/apache2 

References 

 https://docs.bitnami.com/aws/infrastructure/mysql/administration/recover-database-mysql/