This issue only affects Joomla! versions 3.1.4 and 3.1.5 or any version where there are CSS changes
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 it is not enough to do a ctrl+f5
Log off, remove site cookies and log back in
If the problem persists you may want to check to see if your server has mod_pagespeed from Google enabled. 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.x. You do this by logging into the server and then executing
A typical command and location:
sudo touch /var/cache/mod_pagespeed/cache.flush