There many sites for checking your PNR status including government plus private website. Here I will show you how to check your PNR status through IRCTC. One of the simplest and accurate way to check the status of your PNR is to check the status through
irctc.co.in. Below are the steps involved in finding the status of your PNR.

1. Login to your irctc account.

2.Click on Booked History  Under My Transactions Tab.

IRCTC BOOKED HISTORY (CLICK ON IMAGE TO ENLARGE)

3.Enter your irctc password again.

IRCTC RE-ENTER PASSWORD (CLICK ON IMAGE TO ENLARGE)

4. Select the desired pnr no. and then click on get pnr status.

IRCTC GET PNR STATUS (CLICK ON IMAGE TO ENLARGE)

You are done! You can also get a message on your mobile again of your ticket just by clicking Get SMS. 
Sometimes you may not find the status of you PNR upgrading in I R C T C but you can find the real update through India Railways website. Now you will get confirmation message from irctc.co.in if your ticket got confirmed. You need to check the current status after every hour day. Just as your berths got confirmed you will receive a message showing the confirmation of the booking and your berths.

Alternatively you can check your current pnr status here.