couldn't connect to server 127.0.0.1:27017, connection attempt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused : connect@src/mongo/shell/mongo.js:374:17 linux code example

Example: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused : connect@src/mongo/shell/mongo.js:341:17 @(connect):2:6

This method only works if you want to repair your data files without preserving the original files

To find where you dbpath resides- vim /etc/mongodb.conf

check for option dbpath=

(I have dbpath=/var/lib/mongodb)

Default: /data/db/

Typical locations include: /srv/mongodb, /var/lib/mongodb or /opt/mongodb .

Replace the /var/lib/mongodb with your dbpath

sudo rm /var/lib/mongodb/mongod.lock
sudo mongod --dbpath /var/lib/mongodb/ --repair
sudo mongod --dbpath /var/lib/mongodb/ --journal
(Make sure that you leave you terminal running in which you have run above lines, dont press 'Ctrl+c' or quit it.) Type the command to start mongo now in another window.

Hope this works for you ! for those who want to repair your data files while preserving the original files mongo recover