In order of decreasing feasibility,
1) Try another key.
2) Try to open with a card.
2) Call the key master (chabi wala).
3) Try breaking the lock.
4) Climb in through the window.
5) Break down the door.
6) Use termites to make them eat the door.
7) Break the wall.
8) Use Ant Man suit to shrink yourself and go under the door and then open it.
9) Apply principles of quantum mechanics and Quantum Tunnel through the door or the wall and then open it.
10) Acquire enough energy to bend space time into a Einstein-Rosen bridge (create a worm hole) and pass through the door and then open it.
11) Create a device to open an inter dimensional portal which opens on the other side of the door and then open it.
Please let me know how it goes for you ;) :D
You are welcome!