Can't install or update apps
Go to the Home screen menu and touch on Settings.
Browse for the applications Manager.
Touch on it to run it. Once it opens, change the tab to ‘All’ and then browse for the app “Google Play Store”.
Press once on it to display its app information. Here, you will get the option “clear data”. Touch on that entry then restart Google Play Store.

If this doesn’t solve your problem, proceed as above but touch on “uninstall updates.”
Hope this works for you:)
I needed to restart my phone for this procedure to work.