If you've accidentally hidden a column, un-hiding it is straightforward.
In your Workstream, look for the button that either says "Hide Column(s)" or "[1] Hidden Column".
Select that button, and you'll see that the hidden column(s) have been unticked. Simply tick them to bring them back into view.
If you're still having trouble recovering a hidden column, or you think the column may have been deleted, please get in touch with us at support@lupl.com.