Re-obtain old legit copy of windows 10 after hard drive change.

[crimson comet]

I recently had to send in my laptop for repairs but after being informed that my hard drive was dead on arrival and the technicians changed my hard drive without telling me I lost all my data on the old one including my old windows 10 that I upgraded from my windows 8.1 during the free upgrade period. They gave me a replacement windows (not mine) in the new HDD but its key is blocked making it unable to activate. My question is how can I get the legit windows 10 upgrade i got during the free period again or will I have to purchase a new key? Will using the key I used for the windows 8.1 work?

The technicians already sent my old HDD in so I'm not going to get it back sadly. I have tried recovering data but I only managed to pull a small amount out which are mainly personal files. I have also tried talking to the technicians about it but they said they will not claim a new windows for me because my laptop was originally a DOS and didn't come with a windows sticker to prove it.

 

[Paul NZ]

Get the mediacreation tool download the ISO. Use rufus to put it on a flash drive. Then reboot , boot from it

If it was previously activated, it should activate once you get online

 

[captaincharisma]

the windows 10 free upgrade doesn't require a key so like was said above, once you get back online after reinstalling windows 10 it will reactivate

 

[USAFRet]

As above, but when you boot from the USB or DVD you create, wipe everything that is on that drive.
Install the OS from the thing you created.

When it asks for the license key during the install, select "I don't have a product key"

It should activate itself when it goes online.