This problem may occur because you misspelled configuration on /etc/nginx/nginx.conf.
When you type command
$ sudo service nginx restart and the terminal response is fail
To investigate this problem, you need to run;
$ sudo nginx -t
Now you now where the error is.
And to see what command is available, you can type;
$ nginx -h nginx version: nginx/1.8.0 Usage: nginx [-?hvVtq] [-s signal] [-c filename] [-p prefix] [-g directives] Options: -?,-h : this help -v : show version and exit -V : show version and configure options then exit -t : test configuration and exit -q : suppress non-error messages during configuration testing -s signal : send signal to a master process: stop, quit, reopen, reload -p prefix : set prefix path (default: /usr/share/nginx/) -c filename : set configuration file (default: /etc/nginx/nginx.conf) -g directives : set global directives out of configuration file