My laptop's HDD has just gone bad. The OS and recovery partitions are corrupted so I can't recover Windows anymore. However I've backed up Windows' license according to this tutorial before, therefore I download a fresh Windows 8.1 ISO to reinstall and intended to restore the license later. But the Windows installer keeps asking for the product key which I don't know because it wasn't printed on the laptop anymore.

So can I get the key from the above license files (data.dat, cache.dat & tokens.dat) or from the recovery partition (where most files are still left intact)?

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    Use a Linux LiveCD and try what's outlined here: How do I get out my embedded Windows 8 key from a Linux environment? Then com back and let us know if it worked or not. :) – Ƭᴇcʜιᴇ007 Jun 25 '15 at 15:05
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    I suspect that you are trying to install a Windows version that is different from the version which was originally installed - e.g. maybe your laptop came originally with Windows 8 and not 8.1. In that case the product key that is stored in the BIOS is a Windows 8 key which you would need to install and then upgrade to 8.1. – whs Jun 25 '15 at 15:22
  • Windows 8.1 are embedded into the firmware. Any installation disk will automatically detect your license and use that. There are numerous duplicates of this question. If its not being detected then your either using the wrong version of Windows 8.1 or it didn't actually come with Windows 8.1. – Ramhound Jun 25 '15 at 15:51
  • After booting the installing disk, Windows was installed properly. Last time I tried running setup inside Windows and the key input box always appear without any way to skip – phuclv Jun 25 '15 at 16:26

Make sure you're installing the correct OS. If the product key you're backing up is from a computer that (at first) contained Windows 8, then you need to install Windows 8. It will not accept Win 8.1.

In any case the product code is baked into Windows 8 computers and getting that code is rather simple. There's a portable NirSoft tool that can be executed as a GUI or accessed via command line. Then there's this tool that can also be accessed via command line.

Retrieve those tools from whatever computer you're using to post here. Put them on an external storage medium. Simply boot to the recovery disc like you've done before. Choose "Advanced Options" and select Command Prompt. Navigate to the external storage medium and run either executable, or both for verification. Make note of it's product key output and use that during the OS installation.

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