You'll need to have either a full system backup, discs to restore to factory settings, or an install disc for Windows plus a set of drivers to get Windows back up and working. Then if you don't have a full system backup, you'll need to reinstall your applications. I hope you have your data backed up.
You'll need a 2.5" hard drive, likely SATA but check that it's not IDE. Western Digital and Seagate are the most popular brands, but I've seen a lot of Toshiba ones on the market lately too. I just bought a Toshiba hard drive a couple of weeks ago, and it's working fine - so far so good.
I have a Dell Inspiron N5010 Laptop whose internal hard drive has malfunctioned and I want to replace it. What would be the best brand and model I should go for? I am looking for 500 GB or a 320 GB capacity. I have a budget not in excess of $92 or INR 5000.