Are you sure it's missing and not set to auto-hide?
When auto-hide is active, the taskbar will slide out, leaving only a thin 1 or 2 pixels line on the edge of the screen and it will slide into view when you bring the cursor to that line. It will also slide in view when ther is something in the notification area requesting your attention.
When set to auto-hide, it's good to also set it to "On top".
If you want it to always be visible, just un-tick the auto-hide option. The effect is immediate.
Locking have nothing to do with it's visibility, it just lock it's width, location and non-dynamic content.
Electro, May 2012
