1 year ago i brought a SATA samsung 1TB harddrive and installed it sucessfuly and formatted it however after being away for 2 days and coming back it no longer appears in windows. it spins up, the bios recognizes it but using windows i cannot find the disk. however a 8mb unasignable and a uninitialized partion showed up. however after unplugging one of my other harddrives and trying a different SATA lead and port on the mother board the harddrive shows up again but says the entire harddrive is UNALLOCATED and looks as ready as it did out of the box.
is all of my data LOST on the drive?

i'm running windows XP professional SP3
AMD 64 X2 Dual Core Processor 4800+ (2.51GHz)
2GB of ram

the operating system is on a seperate hitachi 250 GB harddrive

if anyother information is needed please say.
thanks Your post indicates you have the same problem with two drives. Both SATA.
Positive areas of INTEREST:
A software update that altered the SATA drivers.
Partial failure in the PSU.
Some kind of Malware.
Last, but not least;
- component failure on motherboard, e.g.m faulty capacitor.

Now of the above are likely, so here come the questions about did you move the computer, was there an electrical storm, did mice GET into the PC case?

Best guess is your CD/DVD drive is failing and it CONTAMINATES the power supply lines. Excessive current, and high electrical noise. That is a very wild guess, but statistically, CD/DVD drives fail more often. Easy test is to remove all cables to the CD/DVD.
DO NOT TRY TO REFORMAT THE DRIVE!

This will only cause pain and suffering.

Try this program here to find and recover lost partitions

http://www.partition-recovery.com/

Hope this helps

KurtisKurtiskain: Do you need to "purchase" the linked program to actually "recover" the data?I dont remember having to.

There are other alternatives out there though