At 9 a.m. this morning Apache suddenly stopped working on my server. No event seems to have occurred, and nothing shows in the logs as out-of-the-ordinary. FTP, SSH and even cPanel are up and working fine. But Apache is not and no Web sites are accessible, of course.
I've tried restarting Apache via both cPanel and SSH. I get the error:
httpd (/usr/local/cpanel/whostmgr/bin/whostmgr ./reshttpd) running as root with PID 1863
httpd has failed, please contact the sysadmin.
Rebooting, gracefully and forcefully, don't seem to change the situation.
I tried EasyApache to update Apache and restart it, and after a long process I got:
!! Executing '/scripts/initsslhttpd' !!
!! Restarting 'httpd' ... !!
!! Failed to restart Apache. !!
!! Apache restarted, but pid file does not match process list pids.
Also tried "Update System Software" and "Update Server Software" which completed but failed to improve the situation.
Submitted a ticket to The Planet, but I'm very anxious to get my sites back up and running.
Any ideas about what I can try next?

The problem was spotted by The Planet's tech support team. A log file had hit 2G in size! Problem solved.

Consider upgrading to apache 2.x to fix that for the future

or setup logrotate - which will actually solve the problem