Macbook pro does not recognize the hard drive

I am no computer expect, so I wonder if this problem is serious or not. My Mac Book Pro does not recognize the hard drive, when I turn it on, it shows a grey screen with nothing on it then a question mark appears and that's it. I tried internet recovery by pressing alt/option and after connecting to the internet, these options appear: restore using a back up; install lion, or disk utility. In any of those, there is no harddrive to restore, intall lion or repair. there is just an 'image of the disk'.