Error which I got -Inspiron-3541:/etc/apache2/sites-available$ service apache2 reload /usr/sbin/apache2ctl: 87: ulimit: error setting limit (Operation not permitted) apache2: Syntax error on line 237 of /etc/apache2/apache2.conf: Could not open configuration file /etc/apache2/sites-enabled/mysite: No such file or directory Action 'configtest' failed. The Apache error log may have more information. ...fail!
According to the error this file /etc/apache2/sites-enabled/mysite doesn't exist (perhaps you have deleted or renamed it).
If that is not the problem check the messages in the error log (which should be located by default in /var/log/apache2/error.log)