My windows deactivated for no reason.

A common cause is that Windows can no longer find a valid license for the device. That can happen if this is the first install on the PC, if significant hardware changed, or if the device is no longer matching the digital license.

Try this in order:

1. Check activation status:
   • Windows 10: Start > Settings > Update & Security > Activation
   • Look at the message next to Activation.
2. Run the Activation troubleshooter:
   • Windows 10: Start > Settings > Update & Security > Activation > Troubleshoot
   • This requires an internet connection and administrator access.
   • The Troubleshoot option appears only when Windows is not activated.
3. If hardware was changed recently, use the hardware-change reactivation path:
   • In Activation, select Troubleshoot.
   • If the troubleshooter cannot fix it, look for the link to reactivate after a hardware change.
   • This works when the license was linked to the same Microsoft account before the hardware change.
4. If a product key is available, enter it:
   • Go to Start > Settings > Update & Security > Activation > Change product key
5. If no valid license is found:
   • In Activation, select Go to Microsoft Store to purchase a digital license.

If the troubleshooter does not resolve it, contact Microsoft support.

References:

• Fix Windows 10 activation error 0x803F7001
• Using the Windows Activation troubleshooter
• Activate Windows