Calc seems to have disappeared?

Running ubuntu - installed latest LibreOffice version - but cannot open and see Calc from any Pathway?? Acts like it might be minimized but Alt Tab does not show it as open!Help?

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This happens when the window is out of screen area, on another or the size of the “normal” state (not minimized nor maximized) is tiny.
Have a look, if the Calc window is sitting on a different work space.
If you can’t find it anywhere:
Activate the invisible window by clicking on the dock icon.
Hit Alt+Space wich pops up the context menu of the active window.
Choose the “Move” or “Resize” command and use the arrow keys.
Enter confirms the current position/size. Esc discards the change.