Execute .php files code without adding .php after url

Recently i have installed a script. After successfully install. I got in homepage . But then i face the real problem. In navigation or in any link whichever i click i get 404 error. I tried multiple time why getting this. A hour later i found out that, site homepage+ only admin area can be browse. But if i Were to visit other options like settings or sign up/in. Pages i have to manually add .php after urls.

Basically i have lots of this type of internAl code/links. That needs to have php extention after url. So is there any code or tricks to execute .php file without typing it manually? I am on shared hosting. I have access .htaccess file and apache.

Example: site.domain.com/admin/settings = error 404
But
site.domain.com/admin/settings.php
Successfully show settings page.

menu/internal url pointing direct page without .php at the end.

And most importantly i am completely noob in this programing. So any tricks would be great. Although i can edit settings file to add .php after each links, but that is really time consuming+ if i forget to add .php in code. I have to check all of them manually 🥲. Thanks in Advance.