Index of my wordpress installation?

Ok this is a newb question but what is the index file for my site?
https://www.pacificvalleysiding.com

I inherited this site from a previous employee. The main public installation is a hodgepodge of html and wordpress. The 2nd installation is a employee area that I have since redesigned and is working correctly. But the main wordpress installation is giving me allot of trouble. I was trying to update the installation 2.3.3 to 2.5.1 using fantastico on my hosts cpanel. That was not working out. So I tried to update manualy to 2.6. Before I did that I wanted to rename the current folder installation to keep as backup but in the process somehow I lost allot of the content. Until I resolve a backup issue with my host I wanted to change the index.html to a “temporary maintenance” index so people would not see a broken installation. But I can’t seem to wrap my head around it. I’m not good with html, I know my way around enough to edit parts if needed. But replacing my index.html file with a different one seems to have no effect. Where is the root of the website directing to?

Thanks for any help