Unfortunately my solution was to backup the theme files on my server, and replace them with the original files from the downloaded theme.
After that, I made only one single modification at a time to stylesheets, page code, etc – and each time, saved the single change and refreshed the blog to make sure the comments were still working.
It was probably the long way round about it, but it was the only solution I could come up with, barring paying someone to fix it for me, which unfortunately wasn’t a viable option.
Sorry I can’t provide better news! Good luck ??