Reinstall of Mountain Lion deleted everything!!

The other day my 13" Macbook Pro froze. So I held the power button to turn it off and when I turned it back on there was a flashing folder with a question mark. I called apple support and they said to reinstall Mountain Lion, which is what it had when I first bought it Nov 2013 but I had upgraded it to Mavericks. But when it was finished and restarted, my computer was like it was when I first bought it. I went through the whole process of setting it up and creating a user account etc. When I was finally able to look around on my computer I soon realized everything was gone. I've looked in the hard drive in the users folder, but only the account I just made and the folder "shared" is in there. The person on the phone told me it would not erase anything, and yet it did. Is there any way to recover my old user account?