May be it's a hard life for you. Being in a dark cave without a glimpse of sunlight is a torture even for unnormal human mind like you. But maybe since I've been there long enough I could tell you that a cave always have a passage. How can you enter a cave without passage.
If it does not have a passage then it's not a cave from the first time, but may be only a soup bown laid upside down on the dining table. And unless you are a cockroach, you can't be trapped inside there, seriously.