Many people like navigating by keyboard.  It can sometimes be faster and more efficient then using a mouse once you get the hang of it.  Here’s two useful shortcuts that may help in that regard.

To open up Windows Explorer (not Internet Explorer), simply hold the Windows key and press E.  No matter where you are, this will open Windows Explorer.

To navigate up and down, simply use the arrow keys.

To open and close subfolders use the * and - keys on the num pad.  Note that these shortcut keys open and close *all* subfolders on the selected folder, not just one level, so if you have a lot of files and subfolders, opening them may take a few moments.

To open only one level of subfolders, use the + key on the num pad.