Windows 10: Can't activate my window 10

Hi, Microsoft....I think I made the worst mistake of my life. You see I tried to upgrade my laptop windows 10 single language to window 10 pro from Google. I tried it and for a sec I thought it work but now I am suffering from this issue that I can't activate my window 10 which my previous version was actually activated. I don't really know where is the previous product key cause the laptop was given by my father and right now I am trying to figure out how to fix it. Is there any method that doesn't require resetting my entire window or not. Please reply to me. The error message told me I need

:)

 

Windows 10 Tweaks

Pressing “Windows+Pause Break” (it’s up there next to scroll lock) opens the “System” Window.

Windows 10: In the new version of Windows, Explorer has a section called Quick Access. This includes your frequent folders and recent files. Explorer defaults to opening this page when you open a new window. If you’d rather open the usual This PC, with links to your drives and library folders, follow these steps:

• Open a new Explorer window.
• Click View in the ribbon.
• Click Options.
• Under General, next to “Open File Explorer to:” choose “This PC.”
• Click OK

credit to Lifehacker.

 

Windows 10 will not activate Error code 0x803F7001

thanks
I activated my Windows 10 from product key Windows 7

 

DOWNLOAD WINDOWS 10 NOW - Upgrade and ISO direct from microsoft

Click to expand... Yeah I went to that site, why do I need to buy a key?
I won't buy a key, stupid.

I'll revert back to windows 7 then.

When I still was on windows 7, about a year ago I added 4GB extra ram which is a total of 8GB now,
is that causing the problem?