I assumed that your service checks were still active but host checks are the ones you miss. The link I provided is about such problem. If a service check returns OK state, Nagios won't do any host check, until service on that host returns non-OK state. For example I have a host which last check was before 2 weeks, and services on that host are regularly checked. Seems like we had misunderstanding.
So, you say that service checks are stopped also? If so, try to restart Nagios, not reload. And you could try to verify your configuration.
What does web gui on Process Info say?