Are you sure you didn't just accidentally close it down?Check in the Window menu at the top, there's a shortcut to open and close it and perhaps you hit that by mistake? I'm not at my Poser pc right now and I can't remember it, but.. worth a look :)

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.