I have lost my windows product key while changing hdd to ssd, Is there is possible way to get back?

[Madhanvasudevan]

Recently i have upgraded to ssd , installed new operating system on it and the existing windows product activation  transferred automatically to new operating system from my backup hdd. So i have formatted the old windows files in hdd. Now my windows product is lost as well and asks me to activate it. I dont have old backup of windows now. Is there any possibilities to get product key back. 

[CherylG]

Your license key is stored in BIOS and should activate automatically IF you installed the same version of Windows 10 as came on the laptop when new.

ShowKeyPlus can retrieve the key from BIOS:

https://www.microsoft.com/en-us/p/showkeyplus/9pkvzcprx9nv?activetab=pivot:overviewtab

[Madhanvasudevan]

Thanks a lot for the help. I appreciate that. I got OEM key with help of ShowKeyPlus and tried installing the key, i got below error.

"the product key you entered didn't work 0xc004f050"

So i uninstalled the existing product key and tried installing OEM key via cmd, still getting error, I have mentioned the error screenshot below, please check if you could do anything with it. 

What is core edition of windows. how do i get it. I remember i installed Windows 10 clean iso from the website.

[WAWood]

@Madhanvasudevan

In her reply, @CherylG mentioned a key constraint "the same version as came on the laptop" -- which in this case, was an HP OEM version, which you can not download from MS.

If you installed an MS version, that wants a Retail key, and your OEM HP key will not work with it.