Switching worlds

lets say i have i have a map and one of the quests is i have to go into a cave. when i go into the cave it takes me to a new map. My question is how do i make it so the level i just left is in exactly the same condition as i left it when i go back to that level?

if its a single player rpg use game chaeses

i know it involves game caches but i dont know how to do it

Are the maps of bonus campaign locked or something ?
get a MPQ browser and explore it to learn how

I have searched but i can't find the answer can somebody help?

Store all of the required values in caches, and then load then from the caches when the map is reloaded.

is it possible to save the whole map?