Can't load into anything (not even title screen)

The app was working normally until yesterday. It won't get past the loading screen with the gray bars. It freezes and lags out. I've been trying to get back in since it stopped working, but I've only gotten to the the title screen once or twice before it freezes. I don't want to delete the app and redownload it because I'm afraid my only world will disappear. I've relaunched my wifi and restarted my phone, but nothing is working. Please help