Lost nginx.pid solution after restarting or killing the Nginx process

When installing the SSL certificate, you forcibly killed the Nginx process and never got up again:

Restarting nginx daemon: nginxcat: /usr/local/nginx/logs/nginx.pid: No such file or directory
kill: usage: kill [-s sigspec |-n signum |-sigspec] pid | jobspec... or kill - l [sigspec]
nginx not running.

Reason analysis:
nginx pid lost

How to retrieve:

issued a nginx -s stop and after that I got this error when trying to reload it.
[error]: invalid PID number  ""  in  " /var/run/nginx.pid " 
That /var/run/nginx/pid file is empty atm.
What do I need to do to fix it?
nginx -s reload is only used to tell a running nginx process to reload its config. After a stop, you don't have a running nginx process to send a signal to. Just run nginx (possibly with a -c /path/to/config/file)

Run command:

/usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/vhost/ofstack.com.conf

At this point, nginx is ready to start normally.