If a team of astronauts had no communication with Earth, what do they do?

Just a scenario that popped into my mind.

So lets say there’s a team of astronauts in an orbiting space station, scheduled to return to Earth in less than 24 hours.

But for whatever reason (zombie apocalypse, terrorist attack, power outage,) there’s no contact from Earth. They do everything they can to try to get a hold of someone. but no luck. Eventually, their 24 hours run out.

Do they return to Earth (Not sure how the whole re-entry thing works,) or stay in orbit until they get some communication or run out of life necessities (water, food, etc..?)