Hello,
Just a heads up that this is a public forum where users help other users, not the official Microsoft live support chat. Because of that, nobody here is a Microsoft employee and we cannot reconnect you to the live agent you were talking to.
If you want us to help you troubleshoot it here instead, we definitely can.
To get started, what exactly happens when you try to activate Windows? Do you get any specific error codes on the activation screen, or did you recently build this PC or change out a major part like the motherboard?