Windows 10: How to get product key of old OS (Win 7) after upgrading to Win 10?

Before 2 Months, I was using Windows 7 Home Premium in my Sony Vaio Laptop which is running absolutely fine. After the release of Windows 10, I upgraded and then clean install my Windows 7 to Windows 10. But after the upgrade, my laptop becomes too slow. It takes about 10 minutes to boot and 5-6 minutes to start the application.
So now i want to go back to windows 7 but now since its over 1 month, I cannot rollback to windows 7. So I want to perform the clean install the same old Windows 7 but I lost the Windows 7 product key that comes with my laptop. Also the sticker at the back of laptop where the product key is printed is erased.
Now in this difficult situation, how can i get the product key of my old windows 7 in order to install it? Is it possible?
Please help me.
Badly regretting for upgrading my Windows 7 to Windows 10.

:)

 

Recent Installed Win10 OS But I don't have Product key Previously My Os Is Win -7 Home genuine How to get product key for win10 ?

Dear all,

My Old OS Is Win 7 Home Which is Completely Genuine . But Recent I Format And Install New win 10 without Product key also without upgrade reservation.

Now I don't know how can I get My Product Key for activation?

Please Need Some Idea! How To activate My Win-10 ?

How to get Product Key ?

ASAP ANSWER



*** Email address is removed for privacy ***

 

How to get product key after Win 7 to Win 10 update and new HDD

thanks ! used the trouble shooter and it found my key !

 

showkey plus from this forum:
Showkey - Windows 10 Forums

 

Sorry but that won't work if he clean installed after upgrading and has an OEM license. It only say you have an OEM Marker.



It only shows the generic install key for Win10
On windows 7 machines there is no key in the mother board BIOS.

 

Oops. I missed the OP where he said he did a clean install after the upgrade. Yep, you are correct, the previous Windows 7 Product key is gone - unless the OP made a backup image of the Windows 7 or first Windows 10 after upgrade, which they would just restore, so there probably was no backup done.

 

Maybe by posting his forums handle with the "at" sign, @Superfly can help*Smile

 

That is the only one you need for 7. You was ripped-off.

Later versions had a key in BIOS but 7 didn't.

If you have not bought a legit version (and someone has scrubbed off the original OEM number) then you'll have consider buying a new license from MS.

I get given lots of laptops to "repair" which people have bought from a "reputable" seller (from a local shop or ebay or whatever). In fact I've never seen one that was genuinely activated. Never.

As you can't validate your 7 you can't expect your upgrade to be valid.

 

The thing is, even if you could retrieve the product key of the underlying OS, it would be useless. If a valid 7 or 8.1 was upgraded to 10 and the 10 automatically activated, the underlying 7 or 8.1 key is flagged as used and can't be used to activate 7 or 8.1 on another machine.

The key of an underlying qualifying OS is gone and invalid as soon as the upgrade to 10 has been activated.

 

You guys are correct - Windows 7 requires to be restored from a backup that includes the relevent certificate as the key is an OEM generic. (BTW. ..I don't think it's pirated - they would go for Ultimate instead.)

@SunilKunwar - PM me the following registry key - and we'll see if we can set your PC back to factory.

HKEY_LOCAL_MACHINE\HARDWARE\ACPI\RSDT

It contains the OEM marker version in order to match the correct certificate.

(NB: I will respond via PM as it requires Sony proprietry stuff to be installed - which was there prior to your upgrade anyways, but still.)

 

Thanks for showing up Craig*Thumbs

 

100% complete and utter nonsense.

 

Could you tell me why?

My own experience:

I have quite a number of Windows 7 and Windows 8 keys, through MPN and MSDN. I have tested the following:

• Install Windows 7 or 8.1 in a vm or physical computer
• Activate it with a valid Retail key
• Reinstall, use the same Retail key
• This works as often as I want to, I can reinstall and reactivate with the same retail key as often as I want to, almost limitless
• Now upgrade this validated and activated Windows 7 or 8.1 to Windows 10
• Try to use the underlying Windows 7 or 8.1 Retail key in a fresh, clean install of Windows 7 or Windows 8.1, suddenly the key does no longer work; I get (without an exception) the message "They key has already been used"

Summary: I can reuse my Windows 7 and 8.1 keys as many times as I want to, but as soon as I have upgraded Windows 7 or Windows 8.1 to Windows 10 and activated it, the key stops working in fresh new, clean installs.

Please either provide proof that my earlier statement was BS or apologize.

 

Kari, so that means, I can just delete both my Win7(from laptop) and Win8.1(desktop) system images, because they're "done for" now. Not that I ever plan on going back*Smile

 

What I have told is what I have experienced.

An example: I install Windows 8.1 Pro and activate it with a valid key. I reinstall it on another hardware or vm, using the same key, no issues, it activates. I repeat this three or four or eleven times, key is always valid and activates.

Then I decide to upgrade the third or seventh or eleventh activated Windows 8.1 Pro to Windows 10 Pro. It will be automatically activated. I take my Windows 8.1 Pro install media to another machine, install it and when asked for the product key, I give this same key I have successfully used several times. Without an exception I will now get a notification about "This key can't be used as it has already been used in another installation".

It's that simple.