mongodb service not running after changing path I have changed the dbpath of mongodb.conf.
And after that trying to start mongodb service,when I run 

sudo service mongodb start


I get back

mongodb start/running, process 7320


After that I run:

sudo service mongodb status


And getting back

mongodb stop/waiting


When I want to access mongo shell by :

 mongo
MongoDB shell version: 2.0.4
connecting to: test
Sun Oct 28 13:01:36 Error: couldn't connect to server 127.0.0.1 shell/mongo.js:84
exception: connect failed


But when I start mongod as manually by mongod --dbpath=/mnt/data/db it runs fine.
And I can access the mongo shell by mongo command.

I have correct permission for my data directory.

Any clue where I am doing wrong?
It is possible that mongodb.conf is not getting loaded because of wrong location (typically this is /etc/mongodb.conf) or a typo when you launch through service start

Try launching manually

mongod --config /etc/mongodb.conf


to rule out any issues with the conf file.