main page help where to find file to fix mistake

Made the mistake of letting my DH who works strickly in html mess with the main page. He didn't save something right and now nothing on the site works. What do I need to go back and edit to solve this problem? I need to know what directory the file is in so I can overwrite it. Thanks

That would depend whether he understood the template system and messed with the default file or the over-ride one. It would also depend which bit of the main page he messed with (most people seem to head for the header first), but he might also have messed with the files that add text to the main page or the file that controls what is included in there.

Do you have a link to your site, or a more specific description of what and where the problem is.