Keyboard shortcuts 4 Windows Explorer:

Display the bottom of the active window. END
Display the top of the active window. HOME
Display all subfolders under the selected folder. NUM LOCK+ASTERISK on numeric keypad (*)
Display the contents of the selected folder. NUM LOCK+PLUS SIGN on numeric keypad (+)
Collapse the selected folder. NUM LOCK+MINUS SIGN on numeric keypad (-)
Collapse current selection if it's expanded, or select parent folder. LEFT ARROW
Display current selection if it's collapsed, or select first subfolder. RIGHT ARROW