Hi, to tell you the truth you need to fix your hard disk first. Once your hard disk works again, you can have the chance to get your lost data back. Maybe you will ask me why I said "lost data". Here I will explain it to you.
If you hard drive cannot work, you must need to repair it, then here comes the problem-just like our computer OS, if the OS doesn't work, we need to install the system again. What will happen? You will know that all of the files in your partition which the OS is installed there will gone just like formatting it. Repair the hard drive is the same as formatting. So you will lose your data. But you still have chance to get the data back by using software or calling the computer expert to help you a lot.
But one thing you need to pay attention is that after repairing the hard disk, you'd better not put anything new into it 'cause this operation will cause the data overwritten situation. Once it happens, you will lose the chance of recover data.
Here is a post which explains more details, you can check it to see if it can help or not, good luck: http://www.uflysoft.com/data-recovery-mac/mac-files-recovery.html