I'm not exactly sure what you mean by resetting a Sim, but this is what I do when my Sim is glitching or is stuck somewhere. Open up the cheat code box by doing CTRL + SHIFT + C. Then type in moveobjects on. Go into buy mode, grab your Sim, and delete him or her. Go back to live mode and click on his or her icon. This should bring him or her back to your household.