just click and hold anywhere in the open space on the taskbar and drag it
back down to the bottom. If this doesn't work then right click on the bar
and make sure that lock taskbar is not checked and then click and hold and
drag it to the bottom.
Although by default the task bar appears on the bottom of the screen, it can
be on any of the sides you prefer it on. To move it from any side to
another, simply click on an unused part of it and drag it where you want it.
Be sure to click *within* it, not on the edge; clicking on the edge and
dragging will resize it.
If it won't move, it may be locked. In that case, right click on it and
uncheck "Lock the taskbar," then try again.