@kmila47 What you've described is the travel transition failing, which is not uncommon. Unfortunately, it sounds like you may have saved in this state, but if you haven't saved twice since the problem occurred, try loading the backup version of this save. Go into Documents > Electronic Arts > The Sims 3 > Saves, and you'll see a folder for your main save and another folder with the same name plus a .backup extension, e.g. SunsetValley.sims3 and SunsetValley.sims3.backup. Rename the save and delete the .backup extension (e.g. SunsetValley1.sims3), and you'll be able to load that version from the Main Menu.
If this backup is also affected, please let me know what you mean when you say playing another family in the town doesn't work. Can you not load the other household, or can you not switch back to the main one, or something else?