The very first thing you should consider is do you have a spare key that somebody can bring you? If not then you have 2 choices, firstly if you are in a metro area the best thing is to call a professional locksmith. They will help you without damaging your car with specialized equipment. If you are outside of an area where a locksmith can get to you then you have no choice but to try to unlock your car yourself.
Method 1: Shoestring
This might seem crazy but depending on your car if it has a pull-up lock this can really work. Loop it to make a lasoo and you can push it through the window and try to hook the lock.
Method 2: Use a Coat Hanger
Get hold of a wire hanger, untwist it and make a hook that goes inside the weather stripping in the window. Jiggle it around until you find the locking mechanism. It may take some time but it can work.
Method 3: Call the police or your security company.
Desperate times call for desperate measures. If you cannot open the door yourself and there is no locksmith able to assist you then you can try calling the local police or security company they will often have experience in these situations and if you are lucky will help you out.
Method 4: Break the smallest window.
This may sound extreme but car windows are not to expensive to replace. Break the smallest one and you should be able to reach with your arm inside to pull out the lock.