java - ElasticSearch service start command fails -

i trying install elasticsearch in digitalocean.

i have installed elasticsearch, when trying run command start server, "[fail]" message in red color.

sudo service elasticsearch start 

the webpage following : https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-elasticsearch-on-ubuntu-14-04

what it?? dont find log file understand happening there