Mac Pro Early 2008, Installed ML,

Try holding Alt/Option at Startup. This initiates the all-in-ROM Startup Manager, which should draw an icon for each potentially-bootable Volume AND one for Recovery_HD as well.

Choose Recovery_HD and launch Disk Utility. Select your drive by Hardware name and check its SMART Status for "Verified" The select Macintosh_HD (or whatever you have renamed it) and ( Repair Disk ). Repeat until all fixed or it gets stuck.

If all fixed, choose Startup Disk and re-specify your Startup Disk, then Restart.

What does it do after all that?

Thanks for your response, I did this steps. I tried both volumes. none opens.

If you got the icons for potentially-bootable Volumes, your Hardware in your Mac is working, but...

None Opens...

This says you may have damage to the EFIBoot partition that loads the simplest parts of the Operating System and stuff that allows your Mac to load Mac OS X and start up.

If you have an appropriate Installer/Utilities DVD, you can try booting from that, choosing Disk Utility form the Utilities menu, and doing a ( Repair Disk ).

You are probably facing a re-Install of Mac OS X.

Worst case, you may have lost your Hard Drive and all its contents.

The DVD drive drawer can be opened using Startup Manager (Alt/Option key as described before). Once all icons are up on the screen, the Eject key on the keyboard goes "live" and can be used to open the drawer. When a new Disc is inserted, the Startup Manager will re-scan and attempt to consider the inserted DVD as a bootable Volume. If it decides the DVD may be bootable, you will get an Icon for it.

All of this proceeds as if in slow motion, so you must be a little patient.

Boot from the DVD.

answer only the "what language" question, if presented, and do not click continue.

Wait a quarter minute for the MenuBar to be drawn.

Choose Disk Utility off a Menu.

Choose you Hard drive by Hardware_name and check the SMART status.

Click ( Repair Disk )

For good measure, choose Macintosh_HD and click ( Repair Disk ).

Repeat until it comes clean or reports an unfixable error.

It has to be the DVD that shipped with that exact model, or a "Full Retail" DVD. Otherwise it does not have all the Drivers needed to boot your Mac.

Apple Hardware test is very, very, simple and self-contained.

Once in a long while there is stuff on one of the drives that, when loaded up to mount the drive, is "poisonous" to the system and it crashes.

The test is to pull the hard drives, and just attempt to boot to the DVD.

This sounds like an exercise in futility, since the idea of booting to the DVD was to use its Disk Utility to Repair the Hard drive. But it is an important test, because a Mac that cannot boot to an appropriate Installer/Utilities DVD has a Hardware problem.

I think it is worth taking it to the genius bar. An Appointment for an evaluation is free, in warranty or out.

My guess is that the Mac OS on your Hard Drive is severely messed up, and that you will end up re-Installing completely or possibly even replacing the Hard Drive.

I think if since you passed Apple Hardware test, if you can boot to the DVD with the Hard Drive removed, there is likely nothing else wrong with your Mac.

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If you need to stop the reboot cycling, press and hold the power button to power it off.