I have hdfc bank net banking on my hdfc bank account. Can I use it to recharge my mobile phone online. I have reliance prepaid phone. If I can recharge online then it will be real help because then I will not need to go to retailer when balance is out in middle of night.

Yes you can recharge online through HDFC bank.
This is link to recharge online for HDFC bank :
https://invas01.euronetworldwide.com...px?custid=hdfc

You need to have HDFC bank netbanking username and password in order to use this recharge facility.