After performing an update it is ESSENTIAL to clear your web browser cache to reload the admin template css.
If you do not do this then the user will not see the toolbar buttons.
Refreshing the browser cache solves this immediately.
[Note : some browser especially chrome can have very sticky browser cache and its not enough to do a ctrl+f5]
If the problem persists you may want to check to see if your server has google_pagespeed enables. If it does, and you want to keep using mod_pagespeed you'll need to flush the server side cache on upgrading to 3.1.4. You do this by logging into the server and then executing
typical command and location:
sudo touch /var/cache/mod_pagespeed/cache.flush