How long can a bat live if it can not get out of a house?

Question

we had our house sided bats were stuck inside walls how long can they live if they cannot get out

Answer 1

It depends on the presence of a food source and the speed of their metabolism.  Bats typically eat daily, as opposed to a snake which might eat and digest one meal over many days.  I doubt many insects are available in your walls for bats to catch, they will likely starve quickly.