Restore a back-up to put it back into the Sims. By doing that, you can happily play with the families in the neighborhood again. After selecting the "Restore from..." option, choosing the back-up to restore and clicking the "Continue..." button in the main screen (Chapter 3) you will be taken to this screen:
There's not much to do here really. Just select the neighborhood to restore the back-up to and click the "Continue" button. If you don't have an expansion pack for The Sims installed, then it's not even possible to select the neighborhood number, so simply click the Continue button then. You can see the back-up's and neighborhood's details in the two boxes on the screen. Click "Abort" to go back to the main screen.
When you click Continue, and a neighborhood exists on the selected number, then the program will ask you if you want to overwrite it. Please note that neighborhoods cannot be password protected so in this case a password won't be asked for overwriting the neighborhood. However, if the back-up has been protected, then it will ask for the password of the back-up before it restores it. If you overwrite a neighborhood, the existing neighborhood will be lost and unrecoverable! Please make sure you don't overwrite a neighborhood that you want to keep, or make a back-up of it first (Chapter 5).
Once the copying of the files is done, you will be taken back to the main screen.
Related chapters: