When I plug in the Toshiba HardDrive, it doesn't show on the drives list. I inserted it before and it showed just fine. I even stored some files inside it. but now it's not showing at all.

Open the file and cick save as. In the window that opens, select the external drive in the list.
or, right click the file and click copy. Open the external drive in my computer and click paste.

go to disk management. If it shows up there try reformatting it

it seems all the files have become hidden go to folder option check show hidden files then check it

Inside the LaCie D2 250GB (300770) external harddrive's case, is a 250GB IDE (PATA) harddrive that is 3.5 inches across in width.

A desktop computer sized harddrive. (May be a Western Digital WD25000JB)

The harddrive plugs into a small circuit board, (Bridge board), and the circuit board has a USB port on it.

Using this Western Digital Passport for an example,

http://www.xbitlabs.com/misc/picture/?src=/images/storage/wd-passport-250gb/p3.jpg&1=1

Scroll down to the second photo, and left-click on it. The case of the external harddrive is shown open.
Inside is a 2.5 inch laptop sized harddrive.
An aluminum tape strip covers the small circuit board, attached at the back of the harddrive.

The second photo down on this page, shows you the small interface circuit board, that the harddrive plugs into, with the aluminum tape removed.

http://www.xbitlabs.com/articles/storage/display/wd-passport-250gb_2.html

(Another design has wires coming from the small circuit board, to an interface the harddrive plugs into )

It is this small circuit board that goes bad in a LaCie. QUITE common.

Solution?

Simple.
1) Obtain a 3.5 inch IDE external enclosure
2) Remove the 3.5 IDE harddrive from the LaCie's case.
3) Install the harddrive out of the LaCie into the external 3.5 IDE enclosure.

An example of a 3.5 IDE (PATA) external enclosure,

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1733195&CatId=2779

For additional questions please post in a Comment.
Regards,
joecoolvette

click start control panel administrive tools ,computer management ,device manager look through all of your devices if you see a yellow question mark?or exclamation mark ! or red x
right click to reinstall drivers or
if you can see your usb but its not working
ports(com&lpt)right click update driver
sometimes the wires inside the cable will be damaged due to bending or stretching or placing heavy equipment upon the cable,
just replace the cable of the hard disk, when you plugged the external disk drive you got that windows could recognize the USB device change the cable everything should work fine again,

check the USB leads that attach to the motherboard usually red-white-green-black make sure they are securely seated and have no dust build up on them dust will cause static and a lot of unforeseen problems also make sure the computers Ram and Cmos battery are securely seated
if this fails to fix the problem
hope this helps you

Hardware problem....
try to use another cable,
or your harddrive is dead... :(
find a tech who can look at it.

Open your command prompt and format the drive type format volume [/fs:file-system]

volume: Specifies the mount point, volume name, or drive letter of the drive you want to format.

/fs:file-system: Specifies the file system to use FAT, FAT32, or NTFS Floppy disks can use only the FAT file system.
Example.........FORMAT E: /FS:FAT32.....Press enter. E: is my second drive

1) have checked bios cannot see hdd mounted.

That is BAD -- the disk-drive could have "died".



2) tried a seagate hdd works fine so connections in laptop seem to be working

That shows that your motherboard is GOOD, but that your disk-drive is BAD.



3) can hear hardrive trying to do something as can hear harddrive usual noise, continous noise for about 5 sec before getting the error message

That is BAD -- the disk-drive is "dying".



4) no rattling or crackling noise from drive apart from the above

That is BAD -- none of the files can be read from your disk.




i have created a ubuntu boot up disk which allows me to access laptop but does shows error when locating hdd,

That is BAD.




once in ubuntu i can access internet but it does not show the windows partition of the harddrive, only shows ubuntu as opearing system, confused.

That is BAD. Only the CD/DVD disk has been mounted -- Ubuntu could not mount the disk-drive.




In regards to ubuntu working does this mean the hdd is ok?

No, it means that your motherboard is working.






and is there anyhting i can try via ubuntu to locate the files?

No. The disk-drive is "dead".




There exist commercial "data recovery" services that can try to repair your device, just long-enough to rescue and copy your files. For example, see: https://services.seagate.com/index.aspx?lng=en-US for a "no data - no charge" guarantee.

you mean you HDD does not show the capacity it holds? try using it on another pc, or even try using it on your friends pc, see if it works?

Hi I have an Acer 5720 with 80GB hard drive, with windows vist, there is very little on it in the way of programs, yet the C drive is appers to keep filling up, D drive is empty, help please, thanks