The elevators are provided with distress button, which can be used to alert the security and maintenance people in case you are stuck inside. Though it works most of the time, but such an accident can happen that you are stuck inside and no one is coming to help after pressing distress siren many times.
The elevator has two doors, one from inside and other outside. The inside door can be opened by bare hands when you are stuck. After opening inside gate you can observe, whether you are stuck on the level of floor or the cabin hangs in between two floors such that you can see upper floor and lower floor at the same time. This technique can be used in both the cases.
Note: Shout and press distress siren to call others in case you are stuck. Use this method wisely only when you can find anyone helping you.