MongooseServerSelectionError: connect ECONNREFUSED ::1:27017, connect ECONNREFUSED 127.0.0.1:27017

Question

my main file

const express  = require("express");
const path = require("path");;
const app = express();
const hbs = require("hbs");
require("./db/conn")
const port = process.env.PORT || 3000 ;

const static_path = path.join(__dirname,"../public");
const template_path = path.join(__dirname,"../templates/views");
const partials_path = path.join(__dirname,"../templates/partials");

app.use(express.static(static_path))
app.set("view engine", "hbs");
app.set("views",template_path);
hbs.registerPartials(partials_path);

app.get("/"  , (req,res)=> {
    res.render("index")
}
);

app.listen(port, () => {
    console.log(`server is running at port no ${port}`)
})

file for mongodb connection name as conn.js

const mongoose = require("mongoose");

mongoose.connect("mongodb://localhost:27017/youtubeRegistration" , {
    // useNewUrlParser : true,
    // useUnifiedTopology: true,
    // useCreateIndex : true
}).then(() =>{
    console.log(`connection successful`);
}).catch((e)=>{
    console.log(`no connection ${e}`)
})

error

no connection MongooseServerSelectionError: connect ECONNREFUSED ::1:27017, connect ECONNREFUSED 127.0.0.1:27017

my service has stopped and an error occur "Windows could not start the mongoDB server (mongoDB) service on local computer

Error 1067 : the process terminated unexpectedly