08-12-2009 09:26 PM
On the handset, press the BlackBerry Menu key to expand the full menu. Select "Show All", the SMS And MMS icon will appear but in a light grey display. Highlight it and select "Hide", it will untick the Hide option and will now appear in the menu as per normal.
08-13-2009 09:53 PM
From your main homescreen, press the BBKey. Select, from that menu, the "Show All" or "Show Hidden" command. If you want to unhide, highlight (but don't select) your hidden icon...then click the BBKey again and select "Unhide".
Hope that helps!