Windows 10: Why isn't my Windows product key not working despite it having worked before?

I received my brother's old computer and have installed new parts on it. I installed Windows 10 Home with a product key and it didn't come up with any errors. I suddenly got a notification that I have to activate Windows. I tried to through the Microsoft store, but it said it wasn't valid. The reason I'm almost certain it's valid is because it is the product key that was shown when scanning my brother's computer with Belarc Advisor. I copied the product key exactly and it still didn't work. Can someone explain please? Thanks in advance.

:)

 

Printer isn´t working after latest update.

After the latest update from Windows, my Canon Pixma ip6600 printer isnt working. In Device Manager it shows up as working properly but when I go to print it isn´t listed as an option in any programs. Troubleshoot suggests it´s a USB 2 printer on a USB
3 port and that that´s the problem but that cant be since it worked fine before the update. I´ve tried to uninstall and plug it back in but that doesn´t work either.

 

Cortana isn´t working

When I hit enter, it did something, but there´s still no Cortana, even after restart. So I tried it again, but now it says that it failed, because it´s already installed and it´s working in PC. So it should work, but Cortana still isn´t here.

 

Razer Kraken V2 - Microsoft Teams (work or school) says "Your speakers aren´t working" & "Your microphone isn´t working"

Since I upgraded to Windows 11 my Razer Kraken V2 can´t be used for calls and meetings in Microsoft Teams (work or school).

While making a test-call there comes a pop-up saying: "Your speakers aren´t working" & "Your microphone isn´t working".

With the newest software installed from the Razer Website (Razer Synapse 3.7.131.11810 & Razer Synapse 2.21) it isn´t working.

When I tried to unistall Razer Synapse and reboot afterwards, it won´t change a thing - the only solution was to unistall razer synaps, uninstall the driver in the device-manager for the headphones and also for the microphone.

No Razer Synapse means no 7.1 sound, nor bass optimization.

I already asked the Razer support about that topic - they said when everything else (beside Microsoft Teams) the problem isn´t on their side?!

A Week ago, everything was working fine under Windows 10, thats the funny thing.

Any guesses what to do, so it will work again with the correct drivers?