accidentally formatted one of the drive on laptop?

My name is macduff and this is the first time i am posting question on forum. I have compact presario laptop with windows 7 operating system installed on it. Hard drive is divided into 3 drives c,d,e, C has operation system installed and other 2 are used to store my personal data. Last night i had connected my external hard drive to it which also has 3 drives. To delete some data from external hard drive i idiotically selected laptop drive and formatted it. After formatting i got to know my mistake. I dint know what to do. Drive which i have formatted had movies, songs, family images and documents of my brothers. I really want all those things back. I would be thankful if anyone could help me out to get back the formatted data.