How do you handle calendar time keeping if you don’t know the date?

If you woke up in a locked room with no idea of the current date, how do you handle keeping track of dates? Is it like the days of the week where you start counting from the first day you wake up? If so, how does that work? Do you treat day 1 as Rosh HaShannah? How does that work with leap months? And Shmita and Yovel? Or do you just not do any calendar bound holidays? If you can see the moon do you lock your calendar to it (If the first day has a full moon, do you treat the first day as 1 Tishrei or 15 Tishrei?)?