If the engine isn’t working then they may have repaired it or taken it to Trellis, Roadtown or Charlotte Amalie where anchoring would be easy or sailed it to Fajardo or San Juan for repairs.
Another option would be to call C&I in Tortola and let them know that your boat was stolen and if it checked out... This will get them fired up and maybe they’ll try to catch the culprits or contact US C&I.