No reason to get scared. At this level (without saving anything) if anything goes wrong, just unplug your router from power and replug it, it will boot in a state as it was before.
Not true with all routers. If I modify a setting, there is no need to save. Unless I am in safe mode, the change is immediate and permanent. Good thing I have a serial port to access the router to get the default config back.
Otherwise, it is no big thing as long as you can afford a new one.