If you were going to get your security deposit back you should have had it by now - 10 to 30 days is typical. I suspect that the landlord will not be returning it. Send one more letter, Certified Mail AND 1st class mail. Leave a copy at the Landlord's door as well. Demand return of your deposit within 3 days. If not returned, you should file in small claims court immediately to get it refunded.
Attorney is Licensed in Arizona, California, and Colorado only. The opinions and comments offered are in the nature of general business advice relating to generic questions that might be raised. The use of this site is not intended to form an attorney client relationship of any kind. The reader is advised that every situation is different and you should always consult in person with a licensed attorney for the particular jurisdiction in question when your legal rights may be effected.