You try to open the door, but it's locked from the inside.
You consider growing a sword out of your head, but that sounds complicated and very painful, plus it could ruin your BELOVED HEAD WEAR! Instead you do what any man of science would do, and make the shape of a very crudely drawn sword. Now all we do is wait for the intense sunlight to take its effect aaaaand,

Voila, you created a GLASS SWORD!

Oh man that's beautiful. What should you do now?