Do this first to see if it helps:
Open Start, type: CMD
Right click CMD
Click Run as administrator
Type in at the prompt OR Copy and Paste these one at a time : (Hit enter after each)
Dism /Online /Cleanup-Image /CheckHealth
Dism /Online /Cleanup-Image /ScanHealth
Dism /Online /Cleanup-Image /RestoreHealth
Also run the System File Checker utility:
Open Start, type: CMD
Right click CMD
Click Run as administrator
At the Command Prompt, type: sfc/scannow
This will check for any integrity violations
Restart your system
Top reasons Windows 10 fails activate:
Not connected to the Internet
Antivirus or Firewall utilities might be blocking product activation
Your computer is behind a proxy server, disabling the proxy temporarily or using chat support can resolve this
Your computer did not upgrade from a genuine version.
The wrong edition is installed.
Your computer is running a Volume License Client requiring access to a Key Management Server (KMS) to activate. This can usually be performed by logging onto your company's domain or VPN.
You can also try restarting, then try activating manually using chat support: