Windows 10: Windows 10 activation after reinstall?

I was having issues with my PC so I decided to do a fresh install of windows with a USB. During the setup, I selected "Do not have product key" Because it said my windows would carry over and activate. However after booting up, The Activate windows sign popped up in the bottom right. And now I have the "Error code 0xC004C003" in the activation tab in settings. My product key was gifted to me by family members around 3 years ago when I was building the PC. So naturally I don't have the key anymore. How do I go about fixing this issue?

:)

 

[Solved] Windows 10 keeps reinstalling KB3119142

I noticed quite some time ago that KB3119142 (Update for Microsoft Visual C++ 2012 Update 4 Redistributable Package) kept reinstalling itself for some reason. At least once daily. Sometimes up to several times a day. I just ignored it. It didn't seem to be doing any harm. And I figured they'd eventually fix it. Well...days turned into weeks, weeks into months, with no end to the problem in sight. It dragged on unsolved for at least the last few months. Literally reinstalling itself hundreds of(at least a hundred, felt like more) times in that period of time.

So I finally googled it a couple days ago. And just got around to fixing it today. Which appears to have worked. And it couldn't have been easier to do. I feel so stupid to have let it intimidate me for so long.*Oops!

Below are links to the thread that I got the fix idea from, and the official MS support info page for KB3119142(from which I quoted the above).
http://www.tenforums.com/windows-up...-windows-10-keeps-reinstalling-kb3119142.html
https://support.microsoft.com/en-us/kb/3119142

 

How to reinstall Windows 10 if my computers used the free upgrade from 7 and 8?

Will windows 10 still accept the license keys from 7 and 8 now if I reinstall my computer?

Does Microsoft keep a list of users who upgraded to Win 10 using their 7 and 8 keys so that when users need to reinstall windows 10 the old keys would work?

Do I need to call in Microsoft to ask them to activate my Windows 10 when I give them my win 7 keys?

Both computers are laptops. The windows 7 machine had the serial printed on the back, and I needed to enter that when I upgraded to 10. The windows 8 machine had the serial built in inside its boot system so I didn't need to enter the key when I upgraded to 10, but I did manage to write down the keys using a fetcher program.

 

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.