I backed up /home to external drive and did clean install 15.10 because upgrade from 15.04 got interrupted. Now the system is up and running but most of system icons and folder icons are missing. In addition the applications in /Home folder are not "installed" such as VirtualBox etc. Are there any solutions available or I must reinstall all apps new. Thanks for helping.
You have to install all the applications again, because you only installed the basic Ubuntu system. Additional applications you had installed on your previous system are still missing, because
/home only contains your users' settings, but no system-wide settings or applications.
When you copy back the
/home folder, the settings for the new installed applications are already set though.