Windows 7: I can't use my Windows firewall, because of the error 0x8007042c

I hope picture explains everything
PS. It has been like this for a year.

A whole year? Wow.

First thing I'd do is run a full anti-malware scan with free Malwarebytes.

Malwarebytes : Malwarebytes Anti-Malware PRO removes malware including viruses, spyware, worms and trojans, plus it protects your computer

I'd next run a System File Checker scan to make sure you don't have any damaged or corrupt system files. Run teh scan from an elevated command prompt (option two, this tutorial.) If any problems are found, run the scan three times rebooting in between each scan.

SFC /SCANNOW Command - System File Checker

See if the firewall can be used. If not, try Methods 2 and 3 in this Microsoft article.

http://support.microsoft.com/kb/2530126

Please post back if any of this helped or not.

Nope.

Are you using another free firewall like ZoneAlarm, Outpost, Comodo, Online Armor, etc or an antivirus suite that includes a firewall? If yes they will disable the Windows Firewall.

Windows defender...Nothing else.

try this:
Download

Windows repair tool

Extract and launch the Repair_Windows. file

Click on Start repairs tab-click on Start

check mark following options alone: (deselect all and only check these)

Reset registry permissions
reset file permissions
Repair WMI
Repair Windows Firewall.
Remove Policies Set By Infections
Repair Winsock & Cache
Repair hosts


Checkmark Restart System When Finished option
click the Start button

System should restart after repair