Apache won't start and there is nothing in the logs
Chance are, if apache isn't starting and isn't logging anything, the error_log is full preventing apache from starting. To double check that, run:
ls -lS | less
If any file is around 2-3 gig (or more), then chances are, that's the problem.
The solution is to remove the logs, restart apache, and then implement preventative measures.
rm -f error_log
rm -f access_log
rm -f suexec_log
rm -f fpexec_log
/sbin/service httpd restart ("/usr/local/etc/rc.d httpd restart" for FreeBSD)
2) Get logrota to rotate daily
perl -pi -e 's/weekly/daily/' /etc/logrotate.conf
perl -pi -e 's/rotate 4/rotate 2/' /etc/logrotate.conf
If apache still doesn't start, check /var/log/messages and try recompiling apache.