Why did all my downloaded apps disappear after installing the update on 01.01.2016?

A

AC Question

why did all my downloaded apps dissappear after installing the update on 01.01.2016?

I installed the automatic update on my Samsung galaxy s4 and then all my downloaded apps like facebook or plants vs zombies disappeared. Additionally all other apps stopped responding. Every built in app gives the error message "unfortunately messages has stopped working" or "unfortunately contacts has stopped working" etc. My Google play store won't even open. Help!!!!