Sorry for the trouble. Here is what I'd try, based on Microsoft's guide for managing devices on a Microsoft account.
1. Remove the old device entry
- Go to https://account.microsoft.com/devices and sign in with your Microsoft account.
- Find the old device and select Remove device.
- Tick the confirmation box and select Remove.
If the old device also affects Microsoft Store downloads, unlink it at https://account.microsoft.com/devices/content (find the device, select Unlink, then confirm).
2. Make sure your current PC can show up
- Windows PCs are added automatically when you sign in to Windows with your Microsoft account. Only Surface devices can be added by serial number.
- Check that you're signed in to Windows with the same Microsoft account you use on the website. In Windows 11, go to Settings > Accounts > Your info to see which account it is.
- A PC owned or managed by a company or school can't be registered to a personal account.
- A device that is already registered to another account won't be added to this one.
- It can take up to 24 hours for a newly registered device to appear.
3. If it still doesn't appear Use Microsoft's Contact Support page, enter your problem, and select Get Help: https://support.microsoft.com/contactus
Official guide: https://support.microsoft.com/accounts-billing/manage/manage-devices-used-with-your-microsoft-account
To help further, please tell me:
- Is your PC a personal one, or provided by work or school?
- Which Windows version do you have, and which account is shown under Settings > Accounts > Your info?
Please don't post your serial number or other personal details.
If this helps, please click Accept Answer.