If apache ( httpd ) fails and says something like: httpd has failed, please contact the sysadmin.

Or just that is can’t work, the first step is to run the Linux command:

service httpd configtest

This should show any errors.

If you still get a error then you need to monitor the error_log file while you try to restart apache:

tail -f /usr/local/apache/logs/error_log

If you have a server with DWHS Website Hosting and you are hell bent on fixing it yourself instead of putting in a ticket, next you might want to run easyapache from your WHM, 90% of the time this will fix any errors.