i just got a motherboard replacement can any one help

First confirm that the installed edition is Windows 11 Home, because a Home product key or digital license cannot activate Windows 11 Pro.

1. Open Start → Settings → System → Activation.
2. Check the edition shown there.
3. If it says Windows 11 Home, continue with the hardware-change procedure below.
4. If it says Windows 11 Pro, you must reinstall Windows 11 Home; entering the Home key cannot change Pro into Home. Back up important files before reinstalling. ^1^

If the old license was linked to your Microsoft account

Because entering the key already failed, use the Activation troubleshooter rather than entering it again:

1. Connect the PC to the internet and sign in as an administrator using the same Microsoft account associated with the old Windows license.
2. Open Settings → System → Activation → Troubleshoot.
3. Select I changed hardware on this device recently.
4. Sign in if requested.
5. Select the old PC from the device list.
6. Check This is the device I’m using right now, then select Activate.

This process requires the digital license to have been linked to that Microsoft account. The troubleshooter appears only while Windows is not activated. ^2^

If the manufacturer replaced the motherboard

If the PC manufacturer or its authorized repair service replaced the motherboard, Windows should normally reactivate automatically. If it did not:

• Contact the manufacturer and ask it to correct activation for the replacement board.
• Check whether the repair provider supplied a Certificate of Authenticity (COA) card containing a replacement 25-character key.
• If supplied, enter that key through Settings → System → Activation → Change product key. ^1^

If activation still fails

The original license type matters:

• A separately purchased retail Windows license may be transferable.
• If Windows came preinstalled on the PC, its license may not transfer to a motherboard replaced outside the manufacturer’s repair process. Microsoft states that a new license may be required in that situation. ^3^
• Record the complete activation error code displayed under Settings → System → Activation. For example, 0xC004F211 indicates that Windows detected changed hardware, while 0xC004F212 indicates an edition mismatch.
• If the edition is Home and the troubleshooter cannot transfer the license, open the Get Help app, search for Windows activation, run its diagnostics, and request Microsoft support. Have the purchase receipt and product key available, but do not post the key publicly.

References

1. [Windows 11](https://support.microsoft.com/windows/activation/activate-windows#reactivate-windows-11-after-a-hardware-change)
2. Reactivating Windows after a hardware change
3. [Windows 11](https://support.microsoft.com/windows/activation/get-help-with-windows-activation-errors#most-common-windows-activation-errors)