Let me start by saying I have a mid 2010 Macbook Pro, all origional hardware, running Mountain Lion. I've never had any problems with it before, but a few days ago the computer froze to the point I had to force shut down. When I restarted, the computer would not boot past the gray screen, and after a while the apple logo was replaced with a question mark.
Since then I have tried the following:
Restarted in safe mode (worked)
Restarted from recovery partition (worked)
Ran Apple Hardware Test from install disc (Even with detailed check, reported all hardware functioning normally)
Attempted to resintall OS X from install disc (OS X Installer did not find Macintosh HD, only the recovery partition)
(From Disk Utility in safe mode, recovery partition, and from install disc)
Attempted to repair disk in Disk Utility (failed 3 times, with this error: Volume bitmap needs minor repair for orphaned blocks. Invalid volume free block count. It should be 18677490 instead of 18677489. The volume Macintosh HD could not be repaired.)
Attempted to erase disk in Disk Utility (failed, with these errors: Either Couldn't unmount disk or File system formatter failed.)
I do not have a clone or backup which I could revert to. I'm not worried about the loss of data, but I unfortunately don't have the option of just trying to revert back to previous settings.
I am writing because I honestly don't know what to make of the results from these tests. DU not being able to repair or even erase the drive, as well as the OS X installer not finding it, leades me to believe that I need a new hard drive. On the other hand, Apple Hardware Test is telling me I have no hardware problems, DU does find the hard drive, and I can boot the recovery partition.