Exceljet

Quick, clean, and to the point

Unhide columns

Windows shortcut 
CtrlShift0
Mac shortcut 
0

Unhide any hidden columns that intersect the current selection.

Notes:

(1) May not work in Excel 2010 on Vista or Windows 7. Discussion and fix is here: http://superuser.com/questions/183197/whats-the-keyboard-shortcut-to-unh...

(2) May not work in Excel 2007. See http://www.techrepublic.com/blog/microsoft-office/office-solution-keyboa...

(3) In Windows 10, there is a conflict with a keyboard switching shortcut. You can resolve by un-assigning the keyboard layout hot key. You may need to un-assign the input language as well.

Windows 10 Change Key Sequence hotkey dialog box

This is a tricky setting to find. You are looking for Advanced Keyboard Settings, under Region and Language. 

Update June 2021: if the shortcut stops working after a Windows update, try assigning then unassigning the switch keyboard layout.

Update February 2022: Can't get the above trick to work. Let us know if you find a solution.

Related videos

The videos below demonstrate this shortcut.
In this lesson, we cover shortcuts you can use to hide and unhide, rows and columns.

Download 200+ Excel Shortcuts

Get over 200 Excel shortcuts for Windows and Mac in one handy PDF.