24 hours in Istanbul after a flight delay and missed connection- help me save this trip

Flight was delayed and missed my connecting flight for my climb in Kilimanjaro. Unsure how that will resolve so very disappointed. Currently have 11 hours until I land in Istanbul and now have a 24 hour layover. I will land around 18:00 local time and my flight is the next day at 18:30. No idea how lodging will end up. What should I do, see, eat, get around? And what time do I need to be back at the airport?

Please help me salvage what has been a very disappointing start to my trip.