BMW 1991 735i locking problem

I have a 1991 BMW 735i. I left the headlights on and locked the car and left until the battery was dead. Now I cannot get into car with my key. I guess the central locking system is down and won't let me in manually either. I had
a guy try to get into it unsuccessfully with a "slim jim". Does anybody have a guess as to how to get into my car?? Should I break a window? Dead battery is under the back seat of car.
Bob

Can you open the trunk? Have you tried going to pasenger side, inserting the key and then while turning the key to unlock position raising the door handle?
Try the search function here and at roadfly.com as well for more solutions.