If you are against this way, you have entered a wrong product key. Observe the product packaging to guarantee that you have the exact product key. Then, pursue these steps to use the "Change product key" utility, and to re-activate Windows Vista:

1. You have to first click on the Start button which is on the left pane of the taskbar. And click on the Computer, and after that click on the System properties on the toolbar.

2. And in the Windows activation section, and click on the Change product key. If you are encouraged for an administrator password or for verification, type your password, or click on the Continue.

3. And after that in the Product key box, sort the product key, and then click on the Next.

Kindly Note:

Confirm the product packaging to check that you are entering the exact product key.

4. Pursue these steps in the Windows Activation Wizard to complete the launch procedure.