Get-CimInstance -ClassName Win32_BIOS | Select-Object -Property SerialNumber

If the laptop is already lost, the serial number command only helps if the device was previously accessible in Windows PowerShell.

To get a Windows device serial number locally, use:

Get-CimInstance -ClassName Win32_BIOS |
    Select-Object -ExpandProperty SerialNumber

A shorter form is:

(Get-CimInstance -ClassName Win32_BIOS -Property SerialNumber).SerialNumber

For a lost or stolen laptop, tracking only works if Find my device was turned on before it was lost, and the device is powered on and connected to the internet. If those conditions were met, sign in to the Microsoft devices page and use Find My Device for that device.

If the device was removed from the devices list, or if Find my device was not enabled beforehand, the location feature will not help recover it.

For Surface devices, the serial number can also be found in the Surface app under Device information if the device is still available.

References:

• Chapter 7 - Working with WMI
• Find the serial number for your Surface device and accessories or Microsoft accessories
• lost my laptop - Microsoft Q&A I try from my phone to find my device location, but it was not visible, and i eliminated from my devices list, hoping that if someone open my device have not access to my microsoft account. Now i don’t know if someone can get access or not and i don’t know the serial number of laptop too. Can i still find my device from my microsoft acount ?
• Device Stolen, how can I find it? - Microsoft Q&A I had my laptop stolen, Is there any way I can find it. When I try and locate it or lock it. It doesnt let me. I really need my laptop and any help will do. Thanks