gmail,google — Gmail account is hacked

Address:

Vadodara, Gujarat

I have gmail account with the address mruga.patel.[protected]@gmail.com.I have access my account sucessfully on 26th sept.2010 at about 12o'clock in the morning.And on the same day at 4o'clock i was umable to operate my account.So i have doubt that somebody has hacked my account.So I want to permenantly delete my acoount.So please advise how to do this as i want to avoide misused of my account.Please do the needful.you can contact me at [protected]@yahoo.co.in.