Hello Jamie,
This "PIN isn't available" error usually happens when Windows can't access the security files it needs to verify your login, often after a Windows Update or a temporary system glitch.
Before anything else, let's try the most common fix. You'll need to be connected to the internet for this.
On the login screen, look for the power icon in the lower-right corner. While holding down the Shift key on your keyboard, click the power icon and then select "Restart". Keep holding Shift until you see a blue screen with several options.
From that menu, go to: Troubleshoot > Advanced Options > Startup Settings > Restart.
After the restart, you'll see a list of options. Press the F5 key to select "Enable Safe Mode with Networking."
If Safe Mode loads, try signing in there with your original password (not the PIN). If that works, you can restart normally and your PIN should be available again.
If that doesn't do the trick, your best and fastest path is to use another device to contact your company's IT help desk. They have administrative tools to reset your password or re-enable your account directly.