Tap the spanner icon on the top right of the title screen. From the menu which opens, please try "Repair Data" then "DL Data Again". Your data will be initialized. (Personal data will not be initialized).
After that, please try reloading Pig Farm 3D. Once data has been downloaded again, Pig Farm 3D will start up.
If the above steps do not fix the problem, please contact our support team.