Who gave you that phone # ?
BE CAREFUL !
Go to Programs and Features > right click at Avast > click Uninstall/Change > select Repair.
Let the system do the repair and then see if you can turn on the firewall.
Slightly off topic............
Personally, I see no reason using a 3rd party anti-virus program.
I have Windows 10 Home and Windows 10 Pro.
In both computers I use the native Windows Defender as the real-time protection, and I use Malwarebytes free edition as my on-demand protection.
That setup has been implemented since first day of Technical Preview build 9841.
I never got infected.