I have a hard drive that I think lost the MBR. Here is what happened:
I had a laptop that I bought in 2005. The battery failed in 2007, so it only ran off AC power. Well one day I clicked "Turn Off Computer" in Windows XP and as it was in the middle of the "Windows is shutting down" screen, I bumped the power cord and the machine lost power. After that it would not boot up. I would get an all black screen with the blinking white cursor. I had no problems with the machine before this, in fact I had recently reformatted and reinstalled windows 2-3 months before.
I messed around with it for a while then stuck it in a box and forgot about it. Fast forward to today and I would really like the data off of it. I bought an external enclosure and plugged it in. Windows installed the drivers fine, but Windows Explorer will not recognize the disk and Disk Management will. It is a 100 GB hard drive, and Disk Management shows it as "Disk 1 - Basic - 93.16 GB - Online" and it shows all 93.16 GB as unallocated. I had just one large NTFS partition on the entire disk when it worked. I am currently running Windows 7 x64 as I work on this damaged disk.
I tried testdisk and it just froze and would not run, but ran fine after I unplugged the disk in question and detected my primary and other external hard drives attached. I have a copy of wGXe Data Recovery Professional that will not recognize the drive either. In fact, with the drive unplugged it will recognize both my regular HDD and my other external, but when I plug in the damaged hard drive, it will not show ANY drive, just stays blank. Also, sometimes when I right click in Disk Management and view the properties of the damaged disk it will show the dialog box, but at other times it will just freeze up the whole Disk Management until I unplug the damaged disk.
If you have any free software or other solutions to suggest, please let me know. I am not ready to pay for software that might not work, since wGXe is an expensive program that I got for free from www.Giveawayoftheday.com and is supposed to be professional and work great, but it cannot even detect it.
Could you try fetching the SMART data from that drive, for example with HDTune (look at Health tab). If your drive has damage (Current Pending Sector) then you should fix that first.
Fixing bad sectors can be done with commercial application Spinrite, or you can opt to forfeit those bad sectors and overwrite them with zeroes, and let the data recovery do its thing to recover what is recoverable.
I would try getting the SMART data first; and DO NOT WRITE to the device unless you know what you're doing.