Firewall shows "Off" after attempt to set up Network

I tried unsuccessfully to set up a home network through the Windows Setup
Wizard. During the process, I selected "Turn on file and printer sharing"
which disabled my Windows Firewall. Now that I don't want to utilize the
network, I can't get the firewall back on. When I go to the Security Center
it shows the firewall as "Off" and there's also a red shield with an X
through it in the taskbar. The problem is that even though the Windows
firewall screen shows "On (recommended)" I can't get rid of the red shield or
activate the firewall in the Security Center.

I would like help turning back on the firewall, and I don't need the partial
network I created. Thanks in advance for your help.