Hi!
I always make a backup of the config prior to updating the game, as sometimes it will be overwritten. If the configuration file syntax did not change, you can replace the default config with the backup copy and everything should start as before.
If the server config got overwritten by accident and you do not have a backup, configure the text file again with the same settings you used when creating the map you want to continue. It should then also load normally.
Also I'm pretty sure there might be a way to call the game with a direct path to a world to load, but I don't know that from top of my head...
