I am running SQL server on my box. I want to be notified if my service stops by email

in services snap-in, you can configure service recovery action to run a script that notifies you when the service stops. You can also attach a task to service manager's "service stopped" event in event log. In any case, checking service state is not the most reliable way to monitor sql server. I would strongly recommend using SCOM or a third party system monitoring solution instead... or at least setting up a task that will check your database state by running a test query against it and alert you by mail in case of failure.