If your insurance didn't cover another driver driving your car, you may not have coverage.  If the other driver had his own insurance to drive (not tied to any vehicle), he may be covered but you would need to sue him.

If your insurance company's policy basically doesn't kick in if someone else is driving your car (i.e., not like if you were in a car accident wherein you were driving and someone else hit you), then you may wish to contact your state's dept of insurance to see if there are any rulings/regulations that would require your insurance company to practice good faith and cover your damages.