MS big update but now not a W10 with key.
Having been so disenchanted with my Lenovo quad i5 PC that I stuck it in a spare room and forgot about it, yesterday I took it out and let it update.
The W10 was a correctly carried out free upgrade from 8.1 home and worked okay. Now it was not showing as authenticated. Trying to authenticate it gave me a screen with a request for a key. I've never had one. And no, there's not one on the Windows hologram.
Stuffed, yet again.
I got back in by using my Windows sign in and that works, but I want to sell this . . . object and any purchaser will of course expect a licensed copy of Windows, which I felt sure I had.
Any ideas what to do. Lenovo won't play with folk after one year, and this machine was boxed for that time.