Can't find the front page that a developer started but didn't finish

Hi
Very much a novice.
I built a website then decided that I wanted a different look and particularly want ‘formulae’ on my front page so hired a (overseas) developer who said he could do it, turns out he could but then disappeared before successful completion.

At the moment the developers front page is showing but with simple spelling mistakes and a broken checkout(e-commerce site) and I can’t find where it is to put at least the spelling mistakes right. The page is not under wordpress admin so expect it’s somewhere on my host server wordpress.

I would like to change the developers home page back to my own for the time being until I can decide whether to find another developer to complete his work or to try myself to move it forward.

I have found the developers home page view by going to Themes – active – customise… it shows here but I don’t know how to get to edit it and also how to unpublish it and to make my existing home page the actual home page.

Sorry for rambling!

Eco