How come I get "mysqld.service failed to load: No such file or directory."
The mysql daemon in Ubuntu is packaged as mysql, not mysqld.
sudo service mysql start
That's really all there is to that one.
I got stuck with the same issue and I uninstalled and installed again by following the following commands:
sudo apt-get --purge remove mysql-server mysql-common mysql-client.sudo apt update && sudo apt dist-upgrade && sudo apt autoremove.sudo apt-get install -y mysql-server mysql-client.