You could notify the police, for one.
You could also file a Warrant in Detinue with your local Small Claims Court at the appropriate General District Court (I assume it's Fairfax).
http://www.courts.state.va.us/forms/district/dc404.pdf
They'll issue a summons to your former friend. If she shows, you'll both take your case before the judge. If she doesn't, you'll win by default judgment and the sheriff will be empowered to seize your property back for you.