So, when you activate the throttle, SOMETHING does happen, just not what you expect, right?
If you hit the light switch, and the lights flicker and go out, you don't think the problem is in the switch, do you?
High odds it is not the throttle. Also high odds it did not "just stopped working". Describe your last successful ride, and EVERYTHING which happened to the bike after that, up to the point the motor stopped running as it should.