How to recover data in formatted hard disk and already installed a new OS

Help how to recover formatted hard disk and already installed a new OS but not yet installed applications.

Edit: I have two 500g hard drives lets say HD1 has my personal files and the other is HD2 where I need to install my OS, but I accidentally formatted my HD1 and installed the OS on it.

I just want to know if I can recover some data on it estimated 200g of data.