When faced with an infinite loop of stairwells, remain calm. Repeat the following mantra to yourself: "I am not lost, I am simply... ... lost in a stairwell.
Take a deep breath, and try to find the exit. If you're still lost, contact the authorities.
Or, if you're feeling particularly adventurous, take the stairs... into the void.
Disclaimer: The authors of this guide are not responsible for any lost souls or existential crises caused by the contents of this page.