Provided info by you is SO huge... so i can only advice.

1. run nginx - it works? goto step 2
2. run nginx with php, see info.php with phpinfo() insie? goto step 3.
3. run nginx with php and global host rewrite to this index script. It works ? go to step 4.
4. run nginx with php and anabled error reporting (logs/display anything). do typo in script. see error? good. now you can TEST whats problem you have with php.

Generaly this is nginx issue not the wordpress. please back to us whan you willl do all these steps.

3) Script code and sample Nginx Configs

<?php var_dump($_SERVER[\'REQUEST_URI\']); ?>

4) PHP bugly code.

<?php vardump($_SERVER[\'REQUEST_URI\']);?>

NGINX (change error log location if you want.)

fastcgi_param PHP_VALUE "error_log=/var/log/nginx/host1.php.error.log";