This firewall issue is commonly found on vista and windows 7 (64 BIT OS)
This is symptom for rootkit on 64 bit systems
if you find a folder called system64
C:/WINDOWS/SYSTEM64(not the sysWOW64)
and a file called consrv.dll
C:/WINDOWS/SYSTEM32/CONSRV.DLL
You're infected by zero access rootkit.It is recommended to contact malware removal forums to remove it first and try the fix
Download both the registry files
Windows firewall - Firewall
Base filtering engine - BFE
Launch them,You should get a UAC prompt now
Click YES & Restart your PC

Now,Press Windows+ R key and type

regedit and click ok

go to

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\BFE

Right click on it-permissions

Click on ADD and type

Everyone and click ok

Now Click on Everyone

Below you have permission for users

Select full control and click ok

Now,open RUN and type

services.msc and click ok

start base filtering engine service and then windows firewall service

You may also be missing security center and windows defender services
Download
Security center -wscsvc
Windows defender - windefend
Launch them and click YES when you get a UAC prompt
Good luck

All credit goes to the below post, NanduPradeep Kumar.

Trying to turn on Windows firewall, getting Error code 0x6D9 - Microsoft Answers