when i play with my family other sims get old with my sims and now most of sims are very old...what happen the next? all the old sims died and the city became empty of people??!!!

Well, when you start a new family and move it in, you can't have this family and the one you currently have in the neighborhood at the same time, so all the other sims will go back to the age they first started. But, you can always go back to playing another family. If you don't want want this, go to options, and click gameplay (i think), or look around in the different tabs, and you can turn off aging for the other family's. Hope this helps!