This is just a quick post to note what worked for me. I found loads of tutorials online but none of them had the full story.
Essentially I had to change my database password. Here is what I did:
Assuming you have ssh access to your DigitalOcean Ubuntu droplet:
Fictional Database Name: wordpressDB
Fictional WordPress User Name: wpUser
Fictional Password: 12345
Open your wordpress wp-config.php (usually located at /var/www/html) and change the password, and make a note of the database name and user.
define( 'DB_PASSWORD', '12345' );
Now change the mySql database details:
mysql -u root -p
UPDATE wp_users SET user_pass = MD5('12345') WHERE ID=1 LIMIT 1;
grant all on wordpressDB.* to 'wpUser'@'localhost' identified by '12345';
Anyway that’s what worked for me, hope it helps someone at some point (probably me, in the future). Generally WordPress is pretty stable, this is the first time I encountered this problem.