I had a live site onto my local server and made some changes in a static page of a custom theme. And now I want to push the edited files onto the live site. I surfed a bit on how to push local site theme onto live site but all answers were to sent whole site files and database replacing the current live site.
Is there anyway to sent only the Theme files onto the live site, a bit beginner friendly ?
As I haven't made any changes that might affect it's database I don't wanna replace everything in the live server.
By made some changes I guess you mean you edited one or more php files (or maybe css files) directly on your local site, then saved your edits, then hit refresh on a browser to see your changes.
That time-honored workflow is sometimes called hot-site editing. Your local site isn't very hot, but it is a live site.
You know which files you edited. So now it's time for the hot-site-patch workflow. Take the files you changed and drop them into your public site, patching the previous copies.
That's how you do it. Does it feel risky and error-prone? Like you could mess up the live site and annoy your site visitors? That's because it IS risky and error prone.
You say you don't want to copy the whole site. But that's the way your kind of changes are usually handled. There are plugins which help you rig up parallel staging and live sites. They usually have a big button marked "push staging to live" for when you're ready to do it.
Or you could put your custom theme in github or some other SaaS revision control system, and pull it live on your web server when you have changes to roll out.