Theme not apearing on localhost?

I have a theme online and one locally and they where both the same for a while until I made changes to the one online. Now when I take the updated online one and place it locally, only the background color and the information in the header loads?

What is the best to replace an older theme with a more updated online version of the same theme?

I tired installing the newr them on to a newly installed blank of WP same thing happened and it’s not the css either?

Thanks