Answer:
You can't.
Explanation:
Not only is it dark, but there is nothing to stand on to reach the ceiling (which all depends if it's ceiling tiles or not), there is no window to break, or door to slam against. There is no way out. No one can let you out unless again the ceiling.
But even so I'm betting the ceiling is solid.
There is no way out unless you ya' know... died
Thwart: To oppose or prevent.
To thwart any outsiders from intruding, I built this wall made of broken bottles.
Buffy realized if the news of the scandal got out it would thwart her chances of becoming the president.
