External HD now shows 'unallocated'???

Hi. I recently (quick) formatted and allocated an external Seagate Barracuda 250GB HD on my Windows Vista system using a SATA HD dock. I copied a load of stuff to it and ejected normally. Now, a month later, I connected it via SATA-USB cable to another computer (Windows 7) and the drive shows as Unallocated. As if I'd never set it up in the first place. I tried it with different cables on a third machine (Windows XP) and a fourth machine (Windows 7) and all the same result. I'm not the most technically well versed and would appreciate any suggestions on getting around this. I'd really like to recover this data. Thanks.
Creed.

 

Well 2 things spring to mind (well my mind in any case).

1. The external enclosure is faulty (probably not since the drive shows up as unallocated).

2. The partition tables / mbrs have become corrupted (highly likely).

See this thread below with a user who had similar type of problem and with a solution. Please read the thread carefully and initially try to use the prog which the OP (dlb) used to access the drive. Then proceed with solution which I strongly believe will work for you also.

http://forums.majorgeeks.com/showthread.php?t=185922

As an alternative boot to a Linux Live cd (Puppy is good 100Mb in size and load entirely to ram) then connect your external and see if it detects.

In your shoes, I would try Puppy first and attempt to recover the data then you can just format the external. I have used the BiNG solution many times myself without any issues and have suggested it also to forum users who have never had issues either but as always there is always a risk.

Good Luck