My Sim has gone Mad!!

The mom and dad of my family were coming home from the hospital with their new boy and girl twins. When the dad came in, he was fine, and started rocking his new son. The mother, however, decided to walk through the door, then the back wall, then through a hill, then through a tree, and started walking upward. The update box in the corner appeared and said "Your sim has gone to the bookstore! She will always remember..." so I quickly saved and exited the game. A few minutes later I got back on and she was standing on the top of some stranger's roof so I just exited again. My sister said this has happened to her before and she had to delete the family and start over... but I don't want to. Is there any way to fix it?