My external 3tb hdd toshiba wont show up in my computer

[Doriven]

My external 3tb hdd toshiba suddenly dissappears and shows only 746 gb unallocated space.I have more than 2 tb info there and i dont wanna format it.i had it fully recognizable and working 2.7 tb( not partitioned) .I use a packard and bell extender that i use it as a usb.i even changed the bios from sata to raid and nothin.i tryed installing rapid storage technology from intel and some of them said that i didnt had the minimum requirements and others just stopped installing.i have win 7 64 bit 2 gb ram 800mhz intel dual core e 5200 2*2.5 ghz processor.anybody help me because i need those infos.
Motherboard: ECS GF7050VT-M5 1.0
Operating System: Microsoft Windows 7 x64 Pro Service Pack 1.0

Processor: Pentium(R) Dual-Core CPU E5200 @ 2.50GHz
Ive tried in another pc with xp installed and all the same .i have to mention that my hdd primarly had a sata connection working as an internal hdd 2.7 tb and when the pins of sata motherboard broke i passed it as an external cable with packard and bell usb and power adapter.it worked fine until i shut down the pc and when i started normally the next day it wont show up and in disk management would show only 746 gb.

 

[kenrivers]

I'm not sure changing the BIOS setting from SATA to RAID was a wise thing to do. That said, have you tried connecting the drive to another computer (maybe a friend's computer) to see if the drive is recognized properly? Have you tried shutting down the computer, disconnecting the drive, rebooting the computer and then reconnecting the drive? If yes, are the results the same?

 

[Doriven]

I'm not sure changing the BIOS setting from SATA to RAID was a wise thing to do. That said, have you tried connecting the drive to another computer (maybe a friend's computer) to see if the drive is recognized properly? Have you tried shutting down the computer, disconnecting the drive, rebooting the computer and then reconnecting the drive? If yes, are the results the same?

I havent tried in another pc .All others ive tried.

 

[kenrivers]

If you get the chance try it with another PC and see what happens. If the problem still exists then it may rule out the possibility that your computer is the problem.

 

[Doriven]

my senses say that the problem is my desktop pc .anyway ill try it and will let you know.

 

[Doriven]

i tried in a xp pc not win 7 and all the same.im really desperate because i dont wanna format my hdd.

 

[kenrivers]

I would try a Windows 7 or later before giving up completely.