Blinking file and ?

13" MBP that was purchased Sept. 2012. I went to download Mavericks, but it stopped halfway through with an error. The computer froze, I had to shut it down and restart. On startup I got the blinking file/question mark. I'm thinking dead hard drive. So I take the drive out and put it in an enclosure and try it on my imac. Drive powers up but is not recognized, not even in disk utility. Any ideas? There are some file I need to recover if possible.