404 Not Found on previously working website - apache

Question

I previously had a website that I was hosting personally on a ubuntu server 16.04 LTS, sort of just a project to show that I knew what I was doing. (Turns out I don't have a clue!)
The site was/is structured such that I have a landing page located in /var/www/html. a second directory located in /var/www/agv-guru and a third directory located in /var/www/owncloud/.
I have an alias set up for both owncloud and the agv-guru folder and everything was working properly for months.
For whatever reason I decided that instead of having a separate server (raspberry-pi) running pi-hole, I would go ahead and install it on my existing server. I quickly realized that my website was down and I un-installed Pi-Hole, which may or may not have made matters worse.
I'm looking for help troubleshooting this one as I am not entirely sure whats going on.
Here is what i know so far.
The folders are still located in the same directory just like before.
The folders are owned by www-data.
The Document Root is /var/www/html.
The Alias is still set up for both agv-guru and owncloud.
/var/www/html/index.html still runs as normal with the exception of one photo not loading that was being pulled from the agv-guru folder.
Webserver is Apache2
Edit 1.
I just cleared the logs hoping to just reload the service but I get an error.
usr#Server:/var/log/apache2# service apache2 reload
apache2.service is not active, cannot reload.
So I ran the status as shown below.
usr#Server:/var/log/apache2# service apache2 status
● apache2.service - LSB: Apache2 web server
Loaded: loaded (/etc/init.d/apache2; bad; vendor preset: enabled)
Drop-In: /lib/systemd/system/apache2.service.d
└─apache2-systemd.conf
Active: inactive (dead) since Tue 2017-10-17 22:16:29 CDT; 58s ago
Docs: man:systemd-sysv-generator(8)
Process: 14594 ExecStop=/etc/init.d/apache2 stop (code=exited, status=0/SUCCESS)
Process: 14577 ExecStart=/etc/init.d/apache2 start (code=exited, status=0/SUCCESS)
Oct 17 22:16:29 Server apache2[14577]: (98)Address already in use: AH00072: make_sock: could not bind to address 0.0.0.0:80
Oct 17 22:16:29 Server apache2[14577]: no listening sockets available, shutting down
Oct 17 22:16:29 Server apache2[14577]: AH00015: Unable to open logs
Oct 17 22:16:29 Server apache2[14577]: Action 'start' failed.
Oct 17 22:16:29 Server apache2[14577]: The Apache error log may have more information.
Oct 17 22:16:29 Server apache2[14577]: *
Oct 17 22:16:29 Server apache2[14594]: * Stopping Apache httpd web server apache2
Oct 17 22:16:29 Server apache2[14594]: *
Oct 17 22:16:29 Server systemd[1]: Started LSB: Apache2 web server.
Oct 17 22:16:36 Server systemd[1]: apache2.service: Unit cannot be reloaded because it is inactive.
Edit 2
sudo netstat -natp | grep ':80.*LISTEN'
Yields
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
1636/lighttpd
Solution
With sborsky's help the solution was found.
When installing pi-hole lighttpd was also installed. This webserver was occupying the port preventing apache from running.