One of these four shortcut keys stops working in Windows versions of Excel:
Ctrl+9 to hide rows
Ctrl+Shift+9 to Unhide rows
Ctrl+0 to hide columns
Ctrl+Shift+0 to unhide columns
If the last one is not working for you, it is because the Windows shortcut to switch language is assigned to Ctrl+Shift. This video shows the Control Panel setting to make Ctrl+Shift+0 or Ctrl+Shift+) start unhiding columns again.