1) Force close your app and reopen it. Get the list of apps open up on your device and shut it down from there. If you don't know how to do this, look up how to force close an app on your device. Upon reopening it, it should work again.
2) If that still didn't work, try resetting your device. Turn it off then on again. Then open Tapped Out and look again to see if it works.
3) The final thing you can try is to uninstall the game and reinstall it.
4) If this doesn't resolve it, there may be a problem with your game. If it is still happening, contact EA for help.