Lost programs and files as well as restore points

I have searched the web, have read a lot of forums and threads but still I can't find anything similar, or even something that close, with the problem I have encountered last night. I have downloaded a freeware called Video Pad which I thought was safe. While installing, I left my computer for a while. Upon my returned, it was breaking my hard drive. I got shocked as there were no error messages. I could only witness how the icons were disappearing one by one from the desktop.

To my panic, I unplugged my computer's battery to immediately turn it off; but it was too late. When I restarted my pc, almost all of my programs were gone as in all of my files. I checked the memory settings of the hard drive to see if my programs were still there somehow. I remembered that in my last check I had 120Gb free storage left, but now it is about 393Gb. Something really went wrong.

I tried to conduct a system restore, but when I checked the restore points, nothing was available. I clicked on the Start menu, hoping that I could find my files in there, but when I used the search bar, nothing was found. When I try searching for a subject of an email, a link will appear but when you click on it, nothing appears.

My other security program has gone as well, which is the Webroot. The McAfee is still there, so I tried scanning the computer system using McAfee and the scanned results say that the system is secured.

The OS of my computer is Windows 7, 64-bit. I just reinstalled some of my programs for work like Microsoft Office and MS Outlook. However, my files saved in these programs are still missing. I could not find my other programs as well like the Internet Explorer and the Skype.

What could have happened?

And what can I do to retrieve my files?

Please help me.

Thanks a lot.