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How to Reactivate Office 2021 After Resetting or Reinstalling a PC
Question details
The user needs to reinstall and reactivate their Microsoft Office 2021 license after performing a system reset due to a security incident.
- Product
- Microsoft Office 2021
- Device & OS
- not provided
- Scenario
- A PC reset wiped the installed applications, and the user must now restore access to their licensed Office software.
- Observed behavior
- Office 2021 requires reactivation, but because the software is licensed for a single computer, the user may encounter activation limit prompts after reinstalling.
Ensure you know the exact Microsoft account credentials (email and password) that were originally used to purchase or redeem your Office 2021 license.
Reinstall and Activate from Your Linked Microsoft Account
Since Office 2021 licenses are tied to your Microsoft account, downloading the installer directly from your account page is the most reliable way to reactivate.
If your Office 2021 was a one-time purchase (such as Home & Student, Small Business, or Professional), the product key is already linked digitally to your account. You do not need the 25-character product key to reinstall.
Open a web browser and go to https://account.microsoft.com/services. Sign in with the Microsoft account associated with your Office license.
Scroll through the page to find your specific Office 2021 product listed under 'Products you've purchased'.
Click the 'Install' button next to your Office 2021 product. Choose your preferred language and bit version if prompted, then click 'Install' again to download the setup file.
Open the downloaded setup file and follow the on-screen instructions. Once installed, open Word or Excel, accept the license agreement, and sign in if prompted to complete activation.
Resolve Activation Limit Errors via Telephone Support
If you receive an activation limit error after reinstalling, you must verify with Microsoft that the license is only installed on one machine.
Avoid Activation Hassles with WPS Office
If you are struggling with strict activation limits or cannot recover your Microsoft account after a PC reset, WPS Office offers a powerful, free alternative. It installs in seconds and lets you open, edit, and save your existing documents without dealing with complex licensing restrictions.
- 1. Download the Installer: Visit the official WPS Office website and click the free download button.
- 2. Install Quickly: Run the lightweight installer to equip your freshly reset PC with a complete office suite in minutes.
- 3. Resume Your Work: Double-click your existing Office documents to open them directly in WPS Office with formatting perfectly preserved.
Frequently Asked Questions
Do I need my original 25-character product key to reinstall Office 2021?
No. Once you have redeemed your Office 2021 product key for the first time, it becomes digitally linked to your Microsoft account. You only need to sign in to the Microsoft Services page to reinstall it.
Can I install Office Home & Student 2021 on two computers?
No. Office Home & Student, Small Business, and Professional 2021 editions are licensed for one computer only. If you need it on a second computer, you must purchase an additional license or use a subscription service.
What should I do if I forgot the Microsoft account linked to my Office license?
You will need to use the Microsoft account recovery tool. Try entering any alternate email addresses or phone numbers you might have used. Without access to the linked account, Microsoft Support generally cannot transfer the license.
