Nextcloud Reinstall after Collabora Online Install Fail?

I’m new to RPis and Nextcloud, but following multiple tutorials [mostly from PiMyLifeUp.com, Tomshardware.com and RaspberryTips.com] I successfully set up a NC server on an RPi 4 8GB, running Apache and MySQL, booting off a Kingston SSD, using a No-IP domain name, and LetsEncrypt certs. It was all working great for a week or so. Then I tried to set up a Collabora Online server - and boom. Not sure exactly how, but it broke my NC server. My first attempt at installing the Collabora Online server was following the directions from the nerdonthestreet.com video (https://www.youtube.com/watch?v=48WrX_Lf1nA). That didn’t work for me, but it didn’t it break anything either. So then I tried using the directions from linuxbabe.com/cloud-storage/integrate-collabora-online-server-nextcloud-ubuntu, and that’s when things went sideways. I’m really not sure, but I’m speculating it might be related to possibly to setting up a reverse proxy [which NotS did not include as a step in his tutorial]?

In any event, I used to be able to access my NC instance via example.mysite.net/nextcloud, but after the second Collabora Online install attempt, I got no response. Nothing. I tried figuring out how to undo what I did during the linuxbabe process, but no luck. Since I moved my data dir to /var/nextcloud [as recommended by the PiMyLifeUp tutorial during the original install], my hope was it was safe to delete all the other NC files in the /var/www/nextcloud directory and try to reinstall. However, now when I go to example.site.net/nextcloud, I get a clear text page that shows the default index.php (it displays the actual code) - vs the default Nextcloud login page I’d hoped to see.

I’d really like to reinstall NC and be able to access my existing data, but at this point I’d just be happy to get NC working again at all.

Is there a way to do a “clean sweep” of NC, reinstall, and then point back to my existing data folder? Or am I stuck starting over completely?

Nextcloud version: 19.0.2
Operating system and version: Raspberry Pi Buster
Apache 2.4.38 Raspbian
PHP 7.3