PHP files keep downloading instead of loading with nginx ubuntu

my configuration file is virtually identical to step four of this tutorial here

here is what my code looks like as of configuration file

server {
	listen 80 default_server;
	listen [::]:80 default_server ipv6only=on;

	root /usr/share/nginx/html;
	index index.php index.html index.htm;

	# Make site accessible from http://localhost/
	server_name 128.199.226.219;

	location / {
		# First attempt to serve request as file, then
		# as directory, then fall back to displaying a 404.
		try_files $uri $uri/ =404;
		# Uncomment to enable naxsi on this location
		# include /etc/nginx/naxsi.rules
	}

	# Only for nginx-naxsi used with nginx-naxsi-ui : process denied requests
	#location /RequestDenied {
	#	proxy_pass http://127.0.0.1:8080;    
	#}

	#error_page 404 /404.html;

	# redirect server error pages to the static page /50x.html
	#
	#error_page 500 502 503 504 /50x.html;
	#location = /50x.html {
	#	root /usr/share/nginx/html;
	#}

	# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
	#
	#location ~ \.php$ {
	# 	try_files $uri =404;
	#	fastcgi_split_path_info ^(.+\.php)(/.+)$;
	#	fastcgi_pass unix:/var/run/php5-fpm.sock;
	#	fastcgi_index index.php;
	#	fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
	#	include fastcgi_params;
	#}

	# deny access to .htaccess files, if Apache's document root
	# concurs with nginx's one
	#
	#location ~ /\.ht {
	#	deny all;
	#}
}