Error mongo db lock, (fix error mongo db turn off when turn off terminal)

Step 1: Remove lock file.
sudo rm /var/lib/mongodb/mongod.lock 

Step 2: Repair mongodb.
mongod --repair 

Step 3: start mongodb.
sudo start mongodb 
 or
sudo service mongodb start 

Step 4: Check status of mongodb.
sudo status mongodb 
 or
sudo service mongodb status 

Step 5: Start mongo console.
mongo