Design problems since changing permalinks settings.

Hi, I am trying to set the permlinks to /%category%/%postname%/ – this wont work unless I put /index.php/%category%/%postname%/. Now when you clink on a category or post, the top part of the design/header disappears. Have a look.. https://www.happyhomesinvestments.com/blog/index.php

On the blogs I have set up the index.php doesnt come up? What wrong with the above blog please??