HTTPS is not responding but able to do CLI

Hi,

How to show if https service is running in Fortigate? Because today, we can't access the web GUI (https) of Fortigate 1000C (v4.0MR3) but still able CLI.

The mgmt1 and mgmt2 have set allow access for https and http.

Even using http, the web GUI still can't show up.

Yesterday, the web GUI still able to access and no configuration changes. My suspect is there is something wrong with https/http service in fortigate.

How can I check the service and restart the service? And what is the impact when I restart the https/http service?

Thank you

Arie