Harddrive not detected in windows

Have you just bought a new harddrive, and it's not showing up under "My Computer"? Or have you borrowed / lent a harddrive from someone, plugged it in, and it's not showing up? The same thing happened to me, and this is how I got it working. This guide is for the old Windows XP, but should be similar for Vista and Windows 7. This guide also assumes that you have the correct jumper and cable settings.

This fix should work on any model, since this is a Windows problem, and not a problem with the harddrive ( you can breathe, your harddrive isn't broken! ). The problem is a conflict within Windows itself, and occurs when you map network devices to a letter ( like E:\, F:\, etc), or use daemon tools (such as in my case), or in other ways "use up" the "next" free letter. If you have two harddrives, and a CD-player, they might be mapped to C:, D:, and E:. If you have F: mapped, by mapping network devices, daemon tools, USB drives (mp3 player for instance), etc, and you have a new harddrive plugged in, Windows wants to give it the "next" letter, which in the case above would be F:\. If it's occupied there will be a conflict, and the new harddrive won't be shown.

First step:
First, check if you can see the new harddrive in BIOS. This guide assumes you can see it there.

Optional:
If you have the model number for your harddrive (I got mine from the website I ordered it from, I couldn't be arsed opening the computer up again and check for myself), you can check if Windows knows it's plugged in.

Start -> Control Panel

Add Hardware

Click Next

It will scan for devices, and when it's done it'll ask if you have connected the device already.

Select "Yes, I have already connected the hardware"

Click "Next"

You'll see a long list of devices. You might recognize some, you may not. It doesn't matter. Scroll down the list until you get to the harddrives. If you don't know the names of the harddrives, look at the icons, they look like square gray harddrives. If you only had one harddrive before, and you see two harddrives now, you know that Windows recognizes its presence. This guide assumes the harddrive is shown in the list.

You can now close the guide, we only used it to make sure that Windows knows it's there.

Second step:

RMB (Right Mouse Button) on "My Computer", select "Manage".

In the new window that appeared, choose "Disk Management" (subcategory of "Storage")

Your right side of the window should be split in an upper and bottom part. The upper part shows the installed harddrives, C:\, and if you had another device, also something like D:\. In the bottom part of the window, you should see one more drive than is listed in the upper window. That extra drive is your new harddrive, and it's not shown in the upper window because it has no letter assigned to it. Identify your new drive (the one with the gray bar, or the one that has no letter in its name).

RMB (Right Mouse Button) on the bar of the drive

Choose "Change Drive Letter and Paths..."

Assign a letter to the drive, and you're done!

If you can't assign a letter to the drive, it means you'll need to defragment the harddrive (most likely you had planned this anyway). So instead of choosing "Change Drive Letter and Paths...",

Choose "Format".

And go on from there. If you managed to plug in an internal harddrive, you should know how to format a drive. =) And all you need to do if wait for the format to complete, and it'll pop up in "My Computer", like the rest of your harddrives.