Hello Paul,
Thank you for keeping us updated and apologies for late response.
I would suggest you to follow the steps below and let us know the result.
Step 1: Start the computer in safe mode with command prompt
To do this:
a. When you hit the power button in Windows 8.1 (through Charms Bar), hold down the Shift key when clicking the Restart button.
b. The next screen will present you with three options. Click Troubleshoot.
c. Next, hit Advanced options followed by Windows Startup Settings from the next screen.
d. Your PC will now be rebooted to enable the advanced parameters, which include Safe Mode as well. Once it restarts, you’ll get nine options whereby the following commands apply:
- F4 for Safe Mode
- F5 for Safe Mode with Networking
- F6 for Safe Mode with Command Prompt
**Step 2:**Run the following command
At the Safe Mode command prompt type the following command and press Enter
net localgroup "Administrators" "Local Service" /add
Note: Put space after every word/command.
You should see a "The command completed successfully" message.
Type Exit and press Enter
Restart the computer in normal mode and check the status of Network and Sharing Center.
Hope this helps. Kindly let us know the update.