Install unity-lens-files by entering the following commands in the terminal:
sudo apt update sudo apt install unity-lens-files
Description:
File lens for unity
This package contains the "file" lens which can be used inside Unity to browse your files.
Homepage: https://launchpad.net/unity-lens-files
Version: 7.1.0+17.10.20170605-0ubuntu2
Section: universe/gnome