Laptop automatically updated in October, have Version 1809 on Lenova Thinkpad with Bluescreen error

[SebringSue]

PC won't start. Has Blue Screen to recover Windows...don't have recovery media for Windows 10..What can I do? And where can I find product serial number?

[#2]

Download Windows 10 and create an ISO file: https://www.microsoft.com/en-us/software-download/windows10

your serial number/product key must be tied up to your account and Windows will use digital activation to automatically active once you log in with your Microsoft account in Windows 10.

use this guide if the hardware of your PC changed:
https://support.microsoft.com/en-us/help/20530/windows-10-reactivating-after-hardware-change