@meetdilip Ok if all else fails, try this. (I've just attempted it and everything worked fine, so here goes this will remove everything but your posts and put them back.) Go to your root folder:
sudo rm -r -f nodebb
git clone https://github.com/NodeBB/NodeBB.git nodebb
This will delete all nodebb files and download them fresh. All your plugins will be removed along with any style settings etc though, but your posts will still be there. If it's still not working, then I'd imagine you have further issues, but this should solve it.
In nodebb setup, enter http://<your servers IP address> then just press enter to accept all defaults, it should find your existing database.