/regeneratechunk

This command can be used to reset chunks to their first generated state. Command syntax: /regeneratechunk <from> [<to>] When used, this resets the chunk to its initial, first generated state at the <from> block position (through the <to> block position, if set) in the dimension of the command's execution.

BE CAREFUL!

Doing this in the chunks you are in will erase all entities and builds in the selected chunks. This is reserved for cheats only.