Samsung Galaxy S3 Stock Calendar Entries Gone! I have a Samsung Galaxy S3 running Android version 4.3. I have always used the stock Calendar app that appears on the home screen of my phone. Recently I installed the Google Calendar app to see which I liked better. I decided I liked the Calendar app that came with my phone better and I uninstalled the Google Calendar app. Since doing that all the entries on my Calendar are gone. It no longer syncs with my Google calendar online. When I go to Menu>Calendars all the calendars that it normally syncs with Google are gone. Sometimes when I open this they are there and checked, but when I click on Done then they all disappear again. When I try to add an existing calendar and enter my gmail address and password it tells me that an account for that user already exists. I am beyond frustrated. I wish I'd never tried the Google Calendar app. All I want is to go back to being able to use the stock Calendar app for my phone and have it sync with my Google calendar online as it did before. Any ideas or suggestions?
Same happened to me. I just reinstalled the google calendar app and all my entries returned on my Samsung calendar.

I think you just need to have the app installed to make it all work properly; I've never actually used the google calendar app which is why I uninstalled it. 

Hope it works for you too.