Localhost/5000 not working. How do i get this ro work when i run node server.js

i have a problem, which when im trying to run my localhost/5000 its not working. I cant also get and post data on postman because of that. Anyone has an idea of how i can fix this ? However when i run the code it is showing that it is connected to my DB. I have also create an env file with the DB link and set the PORT to 5000

Here is the code:
server.js

const express = require('express')
const mongoose = require('mongoose')
const cors = require('cors')
const fileUpload = require('express-fileupload')
const cookieParser = require('cookie-parser')
const PORT = process.env.PORT || 5000

const app = express();
app.use(express.json())
app.use(cookieParser())
app.use(cors)
app.use(fileUpload({
    useTempFiles: true
}))

//connect to db

const URI = process.env.MONGO_URL
mongoose.connect(URI,{
    useCreateIndex: true, 
    useFindAndModify: false,
    useNewUrlParser:true,
    useUnifiedTopology:true
}, err=> {
        if (err) throw err;
        console.log('Connected to Mongo DB')
})

// app.get('/', (req, res) => { 
//     res.json({msg: "Welcome"})
// })

app.listen(PORT, () => { 
    console.log('Server is running on port', PORT)
})

app.use('/user', require('./routes/userRouter'))

package.json

{
  "name": "Webapp",
  "version": "1.0.0",
  "description": "",
  "main": "server.js",
  "scripts": {
    "dev": "nodemon server.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "bcrypt": "^5.0.0",
    "cloudinary": "^1.23.0",
    "concurrently": "^5.3.0",
    "cookie-parser": "^1.4.5",
    "cors": "^2.8.5",
    "dotenv": "^8.2.0",
    "express": "^4.17.1",
    "express-fileupload": "^1.2.1",
    "jsonwebtoken": "^8.5.1",
    "mongoose": "^5.11.12"
  },
  "devDependencies": {
    "nodemon": "^2.0.7"
  }
}