You can try and use Recuva/TestDisk to recover the data that was on your disk but your results can and will vary. It's always good practice to have a backup of your content in case something like this happens. Others have had to deal with drive corruption or even OS corruption. If you're dealing with hacking, I'd ask you to invest in an antivirus or at the very least see if your firewalls on your system/route/ISP are functional.