Even if some of these give you errors it should restart Dovecot properly. If it doesn't, then remove the file /var/run/dovecot/master.pid and rerun the above.
Note that I do not guarantee results if my solutions don't work for you, or even if they break something. I guarantee results only if you hire me to work on your server. I'm sorry that I must do that, but I can only guarantee work I do myself.