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I just put a new hard drive in my laptop. I was installing Windows when the power went off, now it says Error loading operating system. What do I do now?

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Do you mean you were installing Windows on your laptop or do you mean it was booting up into windows when you lost power? – Enigman Feb 7 '13 at 1:04
Is there a reason you can't start over, deleting the partition and re-installing from scratch? This is a new drive so it doesn't sound like you'd be losing anything. – Nicole Hamilton Feb 7 '13 at 1:05
Did you get a recovery disk with your laptop? – b-vigilanT Feb 7 '13 at 1:20
I just put the new hard drive in and was installing the operting system and the power went out. I now have the error. I don't have anything at all on the hard drive. how do I delete the partition and start over/ – Tammy Feb 7 '13 at 1:25
Just start over. Put the install CD in the drive and follow the prompts. – terdon Feb 7 '13 at 3:07

As vonbrand advises, check your boot order in the BIOS. When powering it up, you should see a prompt appear that tells you a particular key to press to enter Setup etc (eg. Press F11 to enter setup.) One of the menu items that will appear should include Boot order (or something similar.)

Ensure that the first device listed is your CD/DVD-ROM, then the hard disk. Save your settings. It will then reboot.

As you haven't listed which operating system you are trying to install I'll have to guess which prompts you will get. Check to see if your laptop then boots from the DVD-ROM (you may have a prompt asking you if you want to boot from the CD/DVD etc)

The installation may detect it failed last time and may prompt you to repair or it may look for existing installations and then prompt to repair. You should be presented with an option to repair, don't select this option.

Normally you will probably see an Upgrade option or Custom (advanced) option. Select the Custom (advanced) option.

You will then be asked where you want to install Windows. It should show you all the disks available (eg. Disk 0) and it will most likely show that disk as being used. This is where you should have an option to delete the volume.

Follow the prompts to delete the volume (you will most likely get prompted twice just to make sure). You will then be presented with the disk and unallocated space. The installation should then proceed as normal.

For Windows 7 you might find the following link useful:

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