windows firewall

Not really without knowing more of what has happened.

Have you recently uninsulated something or have you attempted to load another Firewall?

Have you done anything to the system prior to this happening and that includes applying any available MS Patches?

You could try to roll back to an earlier date if you have System Restore turned on but without knowing more of what has happened it's impossible to give you a better answer.

If you click on the Comment button you can provide answers to these questions. Other wise I don't think that we'll be able to help you much more than what has been stated above.

Col