I have a 3TB external drive by Hitachi. I am attaching it to my new computer. I have misplaced the software. the new XPS 9100 does not recognize the hard drive. What are my options? Thanks

open the case , take out the drive , attache it to a computer internally ,youll need a cable or borrow you cd's cable, turn drive on in the bios to see drive ,save , boot an let windows load it , now does it come up as a drive letter an can you scan fix it . right clik that letter , properties , scan an fix. now thats assuming the drives have windows compatible sectoring an software that formatted it for your data to hold on it.
if you get an error before you get into windows then the drive has likely died in one of many ways.

The problem is with your BIOS settings. You need to make sure the drives are set to AHCI in the BIOS.

try to search driver on manufacturer site

A Hitachi USB external hard drive is a device that acts as portable, removable storage for your personal computer. If you need additional space to house files on your computer but don't want to go to the trouble of installing an internal drive inside the case, a USB external hard drive is your best option. These drives are "plug and play" devices, which means that very little can actually go wrong. If you're having problems, fixing them shouldn't take more than a minute or two.

Check your connections. A USB cable needs to be connecting your Hitachi external hard drive to your computer. Your external hard drive's power cable also needs to be plugged into a functional wall outlet, surge protector, extension cord or power strip. Make sure your Hitachi USB external hard drive is turned to "On." An "On/Off" button is present on the front of the unit. If the indicator light around said button is not illuminated, the drive is "Off" and your computer won't be able to recognize it. Press it to turn it on and then try to access your drive again. Format your hard drive. If your Hitachi USB external hard drive doesn't currently have a file system on it, you won't be able to use it to store data. Open up the "Computer" icon in the "Start" menu. Right-click on your USB external hard drive's icon and click "Format." Click "Start." This will install a file system on your Hitachi USB external hard drive. After this process is finished, you will now be able to use your drive. Restart your computer. Certain models of computers (especially older models) won't recognize new hardware unless your computer boots with the hardware already connected. Leave your USB drive plugged in and restart your computer. Once you do this, your Hitachi USB external hard drive should appear as normal in the "Computer" folder with all of your other drives. Hope this helps.

Format drive NTFS sounds like its corrupt, use mini partition wizard...
may also need 3TB Unlocker from manufacturer of Hdd

ry connecting the external hard drive to another computer to recover/backup your data.
When you have such a large capacity hard drive, it pays to have a second large capacity hard drive to backup your data in the event of the other hard drive dying.Hard drives do fail especially if you accidently drop it.

You probably crashed the head and your drive is now a paper weight. It would be most cost effective to just buy a new drive. If you have data that needs recovered you would want to google "data recovery service" and find a local company if the data is very important, however note that a level 3, most likely what you will need, to pull the data will cost you several thousand dollars.
Side note --- if the drive does not look physically damaged and it's still under warranty you can probably get a free replacement out of it.
Side note --- if it is an external drive and it dropped on the cable plugged in then possibly just the external enclosure controller is damaged. You can buy a new enclosure for about $15 online and it's an easy swap of the drive to the new enclosure.
Comment if you need more assistance.

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
if your computer came with a motherboard disk the drivers could be on it
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"
hope this helps

check cables attach... if still not working.. your hitachi may have been damage because your computer can't recognized it.