Redirect to HTTP instead of HTTPS

We have set up the website on our local server and after finishing development we have to handover and set up to client’s server. Initially we have set up to client’s server in http then the client installed SSL certificate for security and loads over https. After they have made this changes the theme is not applied over website and even the dashboard itself is not there and some source files are loading over http instead of https. Now, only the content is loading in one page without applying theme. Please help us to fix this error.

https://drive.google.com/file/d/1gGc3fJlpBgTWPqqPXlhop1kQ1R9PhFdW/view?usp=drive_link