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How to activate or reinstall Windows 7 Professional or Ultimate

Use this guide to activate an existing Windows 7 installation with your product key, or to perform a full reinstallation from a USB drive or DVD.

Click on the link below that describes your current set-up:

Before you begin: Back up all important files. A clean installation can permanently erase apps, settings, and data from the selected partition.


Activate Windows 7

Follow these steps if Windows 7 Professional or Ultimate is already installed on your computer.

1. Open Windows activation

  1. Select the Start button.

  2. Right-click Computer, then select Properties.

  3. Under Windows activation, select Activate Windows now.

Windows 7 Start menu and System Properties showing the Activate Windows now option

Open Computer Properties and select “Activate Windows now.”

2. Activate online

If Windows detects an internet connection, select Activate Windows online now. If prompted, enter an administrator password or confirm your choice.

Windows 7 activation window with Activate Windows online now highlighted

Select “Activate Windows online now.”

3. Enter your product key

Enter your 25-character Windows 7 Professional or Ultimate product key, select Next, and follow the on-screen instructions.

Windows 7 product key entry screen with the product key field highlighted

Enter the product key exactly as provided.

4. Confirm activation

Windows will verify the license. When the activation is complete, a confirmation message appears.

Windows 7 activation confirmation screen showing that activation was successful

Activation was successful.

Activation not working? Take a screenshot of the full error message or error code before contacting support. This helps the support team diagnose the issue faster.


Download and reinstall Windows 7

1. Download the Windows 7 ISO

Select the version that matches your computer's system architecture:

Make sure the Windows edition and system architecture match your license and computer before installing.

2. Prepare your files and drivers

  • Back up all important files to a separate drive or cloud storage.

  • Keep your Windows 7 Professional or Ultimate product key ready.

  • Save the drivers you may need - especially the network driver - to a USB drive.

3. Start from the installation media

  1. Insert the Windows 7 USB drive or DVD.

  2. Restart the computer.

  3. Open the computer's boot menu. The key is often F12, F9, or Esc, depending on the manufacturer.

  4. Select the USB drive or DVD as the boot device.

4. Start the installation

  1. Select your language and keyboard layout, then select Next.

  2. Select Install now.

  3. Accept the license terms, then select Next.

  4. Select Custom (advanced).

5. Choose a disk or partition

For a clean installation: Select Drive options (advanced), delete the Windows partition you want to replace and any system partitions only if you intend to start completely from scratch, then select Unallocated space and select Next.

To keep a separate data partition: Select the Windows partition, which is often drive C:, and install Windows there. Do not delete the partition that contains the data you want to keep.

Important: Double-check the selected disk and partition before deleting or formatting anything. Deleted partition data may be difficult or impossible to recover.

6. Complete the setup

  • The computer will restart several times. After installation begins, allow it to start from the hard drive instead of booting from the USB drive or DVD again.

  • Create your user account and set the correct date and time.

  • Enter your product key when prompted. You can also activate Windows after setup.

7. Install drivers and updates

  • Install the required chipset, network, and graphics drivers.

  • Run Windows Update if it is available.


Contact technical support

If you still need help, email [email protected].

To help the support team identify the issue and provide the best resolution, include:

  • Your order number

  • A screenshot of the complete activation error or error code

  • A brief description of the issue and the steps you have already tried

Customer service hours: Monday-Friday, 09:00-21:00 CET.


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