You probably accidentally and unintentionally dragged it outside the visible screen.
Exit BSPlayer if active.
Goto BSPlayer's installation folder.
(default C:\Program files\Webteh\BSPlayer\)
There will be a file BSPlayer.YourName.xml
("YourName" depends on "your name" as defined on your PC)
This file holds all your settings (preferences).
If you delete it (or place it elsewhere to be edited and re-used later) and then start BSPlayer you will (hopefully) now see BSPlayer's main window (=control-panel) on the visible part of the screen.
BSPlayer will simply have created a new .xml file
You will then have to redo all your settings or if you've placed the original .xml file elsewhere, compare (with BSPlayer inactive) the two .xml files (e.g. in Notepad) with respect to the line
<MainWinPos type="int">[numeric value]</MainWinPos>
and substitute that value in the "old" .xml-file by the value as created in the new file; then save the old .xml-file and place it back in BSPlayer's installation folder (overwriting the newer version).
