ASAP - Fix wordpress website giving 404 error on pages other than home

I have a wordpress site that is giving a 404 error for all public pages other than home/index and needs to be fixed ASAP

- Home/index page is working fine
- Admin dashboard and all functions there seem to be working fine
- all other public pages give 404 error

This may be a a problem with rewrite rules with Nginx, and .htaccess? But I am no expert.
The Freelancer hired will need to diagnose and fix this problem urgently as the site is unusable.

This is a relatively new install on a new server that was working, and now we are have this problem.
Need an expert in;
Control Web Panel
CentOS
Nginx
Wordpress
SSL

We will provide logins for;
Control Web Panel root
Control Web Panel user account
SSH login
Wordpress login

Auto bids or bids that do not demonstrate this has been read will be ignored.
The winning freelancer will need to start work ASAP