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. 

Related videos

The videos below demonstrate this shortcut.
In this lesson, we cover shortcuts you can use to hide and unhide, rows and columns.
Excel foundational video course
Excel Pivot Table video training course
Excel formulas and functions video training course
Excel Shortcuts Video Course
Excel Charts video training course
Video training for Excel Tables