Nginx configuration 404 errors

I must say that the server configuration is only superficial, perhaps the problem is trivial. But I would be very grateful for your help. I got the site for finishing the design and a small revision. The server uses a bundle of nginx and php-fpm. The situation (sorry for the design, the reputation for links was not enough):

 - при переходе по ссылке http://blabla.ru/blublu.php - уходит на
   http://blabla.ru/404.php
 - при переходе по ссылке http://blabla.ru/blublu.pdf - ничего не
   происходит и отображается главная http://blabla.ru, хотя в адресной
   строке http://blabla.ru/blublu.pdf
 - при переходе по ссылке http://blabla.ru/asfasflkjw1312kl (т.е. вбитый
   абсолютный бред) - ничего не происходит и отображается главная 
   http://blabla.ru, хотя в адресной строке http://blabla.ru/asfasflkjw1312kl

As I understand it, when requesting any non-existing link, whether it is a link to a file or to absolute nonsense, there must be either a redirect to 404.php. But this one it's not happening. How to fix it? I apply the nginx settings. Thank you in advance for your answer.

user www-data;
worker_processes  4;

timer_resolution 100ms;
worker_rlimit_nofile 8192;
worker_priority -5; #Увеличитвваем приоритет

error_log  /var/log/nginx/error.log;
pid        /var/run/nginx.pid;
events {
    worker_connections  1024;
}
http {

    server_tokens off;
    include       /etc/nginx/mime.types;
    access_log  /var/log/nginx/access.log;

    sendfile        on;
    keepalive_timeout  65000;
    tcp_nodelay        on;
    client_max_body_size 50m;

    gzip        on;
    gzip_min_length     1100;
    gzip_disable        "msie6";  #Быстрее, но работает только на новых версиях nginx
    #gzip_disable "MSIE [1-6]\.(?!.*SV1)";
    gzip_proxied        any;
    gzip_comp_level     4;
    gzip_types          text/plain text/css application/x-javascript text/xml application/xml $
    gzip_vary           on;

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;
}

Configuration file from sites-enabled:

 server {
 listen 80;
 server_name www.blabla.ru;
 return 301 http://blabla.ru$request_uri;
 }

server {
 listen 80;
 server_name XXX.XX.XXX.X;
 return 301 http://blabla.ru$request_uri;
 }


server {
 listen 80;
 server_name blabla.ru;
 #return 301 $scheme://blabla.ru$request_uri; 
 server_name xxx.xx.xxx.x;
 root /home/hosting/blabla.ru/www/;
 index index.php index.htm index.html;
 error_page 404 /404.php;
 #error_page 403 404;
 access_log /home/hosting/blabla.ru/log/nginx/access.log;
 error_log /home/hosting/blabla.ru/log/nginx/error.log;

location / {
 if (!-e $request_filename){
 rewrite ^/(.*) /index.php?$query_string; #301 redirect
 }
 }

location /r {
 rewrite ^/r/(.*) /r.php?rub=$1; #301 redirect
 }

location /category {
 rewrite ^/category/(.*) /category.php?rub=$1; #301 redirect
 }

location /article {
 rewrite ^/article/(.*) /article.php?rub=$1; #301 redirect
 }
location /pages {
 rewrite ^/pages/(.*) /pages.php?rub=$1; #301 redirect
 }

location /author {
 rewrite ^/author/(.*) /author.php?rub=$1; #301 redirect
 }

location /user {
 rewrite ^/user/(.*) /user.php?rub=$1; #301 redirect
 }

location /register {
 rewrite ^/register/(.*) /register.php?rub=$1; #301 redirect
 }

location /main {
 rewrite ^/main/(.*) /main.php?rub=$1; #301 redirect
 }

location /profile {
 rewrite ^/profile/(.*) /profile.php?rub=$1; #301 redirect
 }

location /logout {
 rewrite ^/logout/(.*) /logout.php; #301 redirect
 }



location ~* ^.+.(js|css|png|jpg|jpeg|gif|ico)$ {
 access_log        off;
 expires           max;
 }
location ~ \.php$ {
 # fastcgi_split_path_info ^(.+\.php)(.*)$;
 # fastcgi_pass   127.0.0.1:9000;
 fastcgi_pass   unix:/var/run/php5-fpm.sock;
 fastcgi_index  index.php;

 fastcgi_param  DOCUMENT_ROOT    /home/hosting/blabla.ru/www;
 fastcgi_param  SCRIPT_FILENAME  /home/hosting/blabla.ru/www$fastcgi_script_name;
 fastcgi_param  PATH_TRANSLATED  /home/hosting/blabla.ru/www$fastcgi_script_name;

 include fastcgi_params;
 fastcgi_param  QUERY_STRING     $query_string;
 fastcgi_param  REQUEST_METHOD   $request_method;
 fastcgi_param  CONTENT_TYPE     $content_type;
 fastcgi_param  CONTENT_LENGTH   $content_length;
 fastcgi_intercept_errors        on;
 fastcgi_ignore_client_abort     off;
 fastcgi_connect_timeout 60000;
 fastcgi_send_timeout 180000;
 fastcgi_read_timeout 180000;
 fastcgi_buffer_size 128k;
 fastcgi_buffers 4 256k;
 fastcgi_busy_buffers_size 256k;
 fastcgi_temp_file_write_size 256k;
 }

location = /favicon.ico {
 log_not_found off;
 access_log off;
 }

location = /robots.txt {
 allow all;
 log_not_found off;
 access_log off;
 }

location ~ /\.ht {
 deny  all;
 }

 location /phpmyadmin {

 #auth_basic "Enter Super Secret password!";
 #auth_basic_user_file /home/hosting/.htpasswd;

 root /usr/share/;
 index index.php index.html index.htm;
 location ~ ^/phpmyadmin/(.+\.php)$ {
 try_files $uri =404;
 root /usr/share/;
 # fastcgi_pass 127.0.0.1:9000;
 fastcgi_pass unix:/var/run/php5-fpm.sock;
 fastcgi_index index.php;
 fastcgi_param SCRIPT_FILENAME $request_filename;
 fastcgi_connect_timeout 60000;
 fastcgi_send_timeout 180000;
 fastcgi_read_timeout 180000;

 include /etc/nginx/fastcgi_params;
 }
 location ~* ^/phpmyadmin/(.+\.(jpg|jpeg|gif|css|png|js|ico|html|xml|txt))$ {
 root /usr/share/;
 }
 }
 location /phpMyAdmin {
 rewrite ^/* /phpmyadmin last;
 }
 }