My LGG4 was fine until the upgrade to marshmallow in January. After the upgrade nearly half of my apps had lost their icons replaced by the android icon. Clicking these, says app not installed. But on google play store, it says apps are installed, so I couldn't reinstall them. Native email was still there but crashed if I tried to open an email. After several days, turning the phone off/on numerous times, the apps 'miraculously' reappeared. All was well until I turned the phone off for a few hours 2 days ago to save battery, when I turned it back on, lots of apps apparently uninstalled again. Play store app crashes, says play services not installed; go to playstore in native browser it says apps are installed, so I can't try to reinstall. I have no idea what's going on or how to try to fix it. Removing battery has no effect.