In order to get back your data, first you must disconnect your hard drive and connect it to a healthy system. Then, you need to install and run powerful third party recovery software on the computer to which the bad hard drive is connected. Make sure that you do not install or save any recovered files on the bad hard drive because it may lead to permanent data loss.
Try using Remo Partition Recovery tool for better results, http://www.myharddriverecovery.net/