Start by trying this:
1) Press “Start”
2) Type “msconfig” in to the Start Search box and press “Enter.”
3) Click the “Services” tab.
4) Find the “Windows Firewall” service. Check the checkbox beside it and press “Apply.”
Alright, if the service doesn’t start at this point (which it probably won’t) do this:
1) Press Ctrl+Shift+Esc
2) Click the “Services” tab
3) Scroll through the list and find the service named “MpsSvc.” You’ll see “Windows Firewall” under the service description.
4) Right click the service and select “Start Service.”
5) Make sure it is set to automatically start.
You can get there also by:
In the Start Search box type services.msc and press the Enter key.
Open up the console and find the service that says Windows Firewall and choose Properties.
Make sure it is set to Automatic and is started.
Once it is running reboot the computer.
If it does not come up automatically at this point something is wrong. Check out your event log.
You can open your event log by:
Click the Start button Picture of the Start button. In the Search box, type Event Viewer, and then, in the list of results, double-click Event Viewer. Look for entries about the time you restarted your machine. Red X’s denote errors.